[求助]大全619

1.        Scientific interest in providing suitable habitats for bottom-dwelling animals such as river clams arises not because they are important sources of human food but from their role as an integral link in the Aquatic food chain.ED

(A) not because they are important sources of human food

(B) although they are not an important sources of human food

(C) not in that they are important as human sources of food

(D) not from their importance as a source of human food（D）

(E) not from being important sources of food for human beings

E为什么错？D中的importance应该不如E中的important吧