Critical Reasoning

Psychologist: Although studies of young children have revealed important facts about the influence of the environment on language acquisition, it is clear that one cannot attribute such acquisition solely to environmental influences: innate mechanisms also play a role. So, the most reasonable question that ought to be studied is whether _______.

Which one of the following most logically completes the passage?

A. language acquisition can ever be fully explained
B. innate mechanisms are a contributing factor in language learning
C. language acquisition is solely the product of innate mechanisms
D. parents and peers are the most important influence on a child's learning of a language
E. innate mechanisms play a more important role in language acquisition than a child's immediate environment

[spoiler]OA:E
Isn't E too strong, when we already have B, a mild answer?[/spoiler]