再问一题．．．语法绝对让人懊恼

41.   Since chromosome damage may be caused by viral infections, medical x-rays, and exposure to sunlight, it is important that the chromosomes of a population to be tested for chemically induced damage be compared with those of a control population.

(A) to be tested for chemically induced damage be compared with

(B) being tested for damage induced chemically are compared with

(C) being tested for chemically induced damage should be compared to

(D) being tested for chemically induced damage are to be compared to（A）

(E) that is to be tested for chemically induced damage are to be comparable with

选Ａ到是能选出来．．．就是不知道后面那个怎么用be compare with....那个be 是怎么回事

被动语态. chromosomes of a population be compared with (chromosomes ) of a controlled population