Studies of the KE family and the FOXP2 gene indicate that:

a. language is controlled entirely by a single gene found on chromosome 7.
b. language is still fluent despite a mutation to this gene.
c. this particular gene is related to one specific aspect of language.
d. mutations affecting this gene lead to highly expressive language skills.

Answer: C

Rationale: The research on FOXP2 is very important, but reveals only how a single gene relates to one aspect of language use.