Read  the  fol...

Câu hỏi: Read  the  following  passage  and  mark  the  letter  A,  B,  C,  or  D  on  your  answer  sheet  to  indicate  the  correct answer to each of the questions from 36 to 42. 

A. It has a history as long as that of civilization.

B. It was just as serious in the past as it is today.

C. It is a fairy recent problem.

D. Ancient societies managed the problem well.