请教GMAT&LSAT CR SECTION 2-19--->beautywawa转移

19.   The U.S. census is not perfect: thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate. Certainly some of the poor go uncounted, particularly the homeless; but some of the rich go uncounted as well, because they are often abroad or traveling between one residence and another.

Which of the following is an assumption on which the argument above depends?

(A) Both the rich and the poor have personal and economic reasons to avoid being counted by the census.

(B) All Americans may reasonably be classified as either poor or rich.

(C) The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted.

(D) The number of homeless Americans is approximately equal to the number of rich Americans.

(E) The primary purpose of the census is to analyze the economic status of the American population.

答案是C.可是我不理解statistical portrait是什么,如果是统计图的话,我觉得B应该是答案.因为如果美国人只有穷人和富人两种的话,在一部分穷人和一部分富人没有被统计的情况下,才能保持文中说的statistical portrait of the nation painted by the census is accurate.

请教

i don't quite understand the correct answer choice C either. but C is the only possible choice if use the process of elimination

B cannot be correct because this assumption must be about statistical information, or about numbers. the sitmulus reads like "basic statistical portrait is accurate... since some rich people go uncounted, and some poor uncounted...". The rich-poor categorization should not matter if the numbers are basically accurate.  

D cannot be true because it talks about the total number of the poor and the rich, but we are concerned about the numbers uncounted.