Sentence Correction

Those who believe that innovations in biotechnology may be able to help alleviate the challenges of agriculture in Africa, which the world community generally agrees are in crisis, are asking plant geneticists and other scientists why they think the situation of small farmers in Africa has grown so dire.

A. which the world community generally agrees are in crisis, are asking plant geneticists and other scientists why they think
B. which, the world community generally agree, is in crisis, is asking plant geneticists and other scientists their thoughts as to why
C. which the world community generally agrees is in crisis, are asking for plant geneticists' and other scientists' thoughts about why they think
D. which the world community generally agrees is in crisis, are asking plant geneticists and other scientists for their thoughts on why
E. which, the world community agrees, are in a crisis, ask plant geneticists and other scientists why

OA is D
if option D could be correct then what makes B incorrrect.? An Expert analysis is needed here. Thanks.