The question asks you to draw a conclusion about sanitary conditions in Britain after the Crimean War that is suggested, rather than stated expressly, in the passage. The best answer is D. In the second paragraph Nightingale’s efforts to reform sanitary conditions in Britain are illustrated by her response to the death rate among enlisted men in British barracks, which is described as unusually high relative to that of neighboring civilian populations. From this, it can be inferred that sanitary conditions in the barracks were worse than in these civilian populations. Choices A, B and C are incorrect: in each, a comparison is made between sanitary conditions in post-war Britain and sanitary conditions elsewhere or at other times. However, because the passage provides no basis on which to make any of these comparisons, all three of these choices are incorrect. The passage does not mention sanitary conditions “in other parts of the world,” as in Choice A; “before the war,” as in choice B; or in “rural areas” as compared with “urban centers”, as in choice C.