chaitanya.mehrotra wrote:A report released by the American Diabetes Association maintains that much of the increase in cases of type II diabetes can be attributed to the poor eating and exercise habits of young Americans.

(A) much of the increase in cases of type II diabetes can be attributed
(B) many of the increase in cases of type II diabetes are attributable
(C) they can attribute much of the increase in cases of type II diabetes
(D) doctors attribute much of the increase in cases of type II diabetes
(E) many of the cases of increased type II diabetes can be attributed

OA A

Here we can consider option D which includes "doctor" but the explanation in the book states that as doctor is not given in the original sentence we cannot say for sure who has attributed the increase in cases. As doctor in the original sentence is not given we can take passive voice sentence instead.
But if we apply the same logic to below question then E should also be not correct as litigators is not given in the original sentence. Please explain this...

With the assistance of informants, cases often can be made against otherwise elusive criminals.

a ...

b Cases can often be made against otherwise elusive criminals with the aid of informants.

c With the assistance of informants, we can often make cases against otherwise elusive criminals

d Otherwise elusive criminals can often have cases made against them with the assistance of informants

e With the assistance of informants, litigators can often make cases against otherwise elusive criminals

OA is E