This text is given:
In the twentieth century, architects in large cities designed structures in a way that reduced noise and yet made living as comfortable as possible. [A] They used such techniques as making walls hollow and filling this wall space with materials that absorb noise. Thick carpets and heavy curtains were used to cover floors and windows. Air conditioners and furnaces were designed to filter air through soundproofing materials. [B] However, after much time and effort had been spent in making buildings less noisy, it was discovered that people also reacted adversely to the lack of sound. [C] Now architects are designing structures that reduce undesirable noise but retain the kind of noise that people seem to need. [D]
But I don't find this question quite right:
According to the passage, making walls hollow and filling this wall space with materials that absorb noise results in
A. filtered air
B. a lack of sound
C. an adverse reaction to noise
D. a reduction in undesirable noise
Apparently the right choice (based on the answer key) is B. And that's ok with me and it makes sense, but what I don't understand is how D can be wrong.
I mean, if B is right (there is a lack of sound), there is also a reduction in undesirable noise. Logically I think that if B is right it automatically makes D right too. But shouldn't there be only one correct answer in a TOEFL test question?
To me it feels like asking if a square shaped image is a rectangle or a square.
Maybe I am missing something here. What is it I am missing?