This is an official practice question for the SAT Reasoning Test:

Along the curve of islands known as the Florida Keys lies a reef of living coral, the only one of a kind in the continental United States. No error.

Instructions for this section:

The following sentences test your ability to recognize grammar and usage errors. Each sentence contains either a single error or no error at all. No sentence contains more than one error. The error, if there is one, is underlined and lettered [I just made the relevant section bold]. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence is correct, select choice E. In choosing answers, follow the requirements of standard written English.

Think hard . . . answer:

D (a kind).

Obviously, in order to be idiomatic, the only one of a kind is incorrect. Our choices are:

  1. the only one of its kind (presumably the implied correction)
  2. one of a kind

Now, normally when ETS wants you to honor a different part of a sentence, it's not going to be up for grabs (it won't be highlighted as an answer choice). If possibility 1 in this disjunction were the absolute right answer, we'd have expected the to be outside of answer choice "C" (the only one).

My highly educated teacher said that if it were his test, he'd go change the answer, but it's College Board's, and I'd just have to *deal with it.


  1. With all the English you know, how could you possibly justify choice 1 over choice 2?

    • You see, I have no choice as a high school student to submit to the test's standards. My best explanation is that, even though the two choices are nearly semantically equivalent, the first might have been seen as closer to the original intention (though technically whatever original intention was equivocal).
  2. Are both technically correct?

    • Maybe I'll bring it up to College Board.

2 Answers 2


I'm the teacher with whom Simon had the original discussion.

Medica's answer misunderstands the nature of the issue here. Simon isn't asking about the mixed idiom "only one of a kind." The problem is really more one of the rules of the game for the SAT. There are two ways to fix this sentence, and each correction requires altering a different underlined portion of the sentence. In other words, two answer choices are defensible. His proposed alternative correction is this:

Along the curve of islands known as the Florida Keys lies a reef of living coral, one of a kind in the continental United States.

This change can be made by altering the underlined portion of the question labeled "C" (as opposed to the indented fix, which is achieved by changing "D").

My points were as follows:

  1. As an appositive, this use of "one of a kind" feels less idiomatic than the intended correction, but it's difficult for me to say that it's syntactically incorrect. There are many instances of people qualifying "one of a kind" with a prepositional phrase (e.g., "She is one of a kind in the classroom"). And it certainly would be correct to say "It is one of a kind in the continental U.S." So why can't we reduce this and use it as an appositive?

  2. Simon's proposed correction also slightly changes the focus of what we're talking about. "The only one of its kind" suggests that there are other similar coral reefs elsewhere in the world but this is the only representative in the continental U.S. The "one of a kind" reading places the emphasis on the uniqueness within the U.S. But this is really an difference in rhetorical focus. I don't detect a difference in propositional content between the two. In other words, both describe the same factual situation. The College Board might well argue that this consideration favors the intended answer, but that strikes me as hand-waving.

  3. This is a "fake" College Board SAT. In other words, it was formed by re-editing old material, and as a result, this test wasn't subjected to the same level of scrutiny that an operational form would be. Subtle editorial changes in an item can introduce unintended errors along the way. In other words, Simon may well have discovered a truly ambiguous question. They are rare in authentic CB material, but not completely unheard of.

By the way, in my experience, when you try to contact College Board with corrections like this (i.e., ones that don't make a difference to students' reported scores), the usual response is a deafening silence.


One of a kind is an idiom. However, it's not used as an idiom in your example sentence. The only one of a kind isn't an idiom; it would be an error used this way.

One of a kind means unique. It is an adjectival phrase (or noun).

  • Announcing the Battle 4 Atlantis, a one-of-a-kind college basketball tournament being held...
  • He was an extraordinary person - absolutely one of a kind.

The only one of its kind is also a phrase meaning unique. The Baku Museum of Miniature Books is the only museum of miniature books in the world. It is the only one of its kind.

The only one of a kind is a strange phrase, meaning the "only unique". Besides being odd (and a tautology), what is it modifying in your sentence?

  • *Along the curve of islands known as the Florida Keys lies a reef of living coral, the only unique in the continental United States. (wrong)
  • Along the curve of islands known as the Florida Keys lies a reef of living coral, unique in the continental United States. (correct)
  • Along the curve of islands known as the Florida Keys lies a reef of living coral, the only one of it's kind in the continental United States. (correct)

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