The simplest way to make sense of this question is to winnow out the answers that can't be correct.
The test question's sentence asserts a logical opposition between finding the tomb intact in the twentieth century and having the tomb X in antiquity, where X stands for one of five words: defamed, denigrated, depredated, derided, or developed. So the task is to figure out which of the five words works in direct opposition to "found intact."
The words defamed, denigrated, and derided share a similar sense of insult, mockery, or unfair criticism—but there is no obvious connection between a lack of defamation, denigration, or derision toward Tutankhamun and the historical fact that his tomb remained intact over the millennia. Likewise, the fact that the tomb was found intact has little connection to whether it was "developed" in antiquity—unless we imagine that parceling it out into condominiums would have resulted in considerably more wear and tear to the structure than it actually endured.
That leaves for our consideration the choice depredated—which means ransacked or plundered. Clearly, "remained intact" stands in strong opposition to "was depredated"; so the only remaining test is whether the whole sentence, with depredated in place, is tolerably logical. In my view, it is: the writer argues that the fact that the tomb escaped the depredations of grave robbers (and so remained intact through many centuries) is evidence that people living in the area quickly forgot about Tutankhamun and his tomb, and so were not inclined to seek it out and pillage it.
Maybe so, maybe not. But unquestionably an argument that links a tomb's intactness to an absence of depredation makes far more sense than an argument that links the tomb's intactness to an absence of defamation, denigration, derision, or development.