Stacey there is nothing wrong with the explanation in 19th question, even I got the same answer as C but the problem is that what you took as the premise and the conclusion, I totally took or identified the opposite.
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.
I took this as the Conclusion because of the word Certainly. Even when you read the sentence as the above sentence as the conclusion, the overall argument becomes logical. Please rectify if I am wrong. But the answer I get it as C as well.
IT IS TIME TO BEAT THE GMAT
LEARNING, APPLICATION AND TIMING IS THE FACT OF GMAT AND LIFE AS WELL... KEEP PLAYING!!!
Whenever you feel that my post really helped you to learn something new, please press on the 'THANK' button.