The popular belief that to be eloquent a person needs a vast vocabular

The popular belief that to be eloquent a person needs a vast vocabulary is wrong.
On the contrary, people with large vocabularies have no incentive for, and tend not to engage in, the kind of creative linguistic self-expression that is required when no available words seem adequate.

Which one of the following is an assumption made in the argument?

A When people are truly eloquent, they have the capacity to express themselves in situations in which their vocabularies seem inadequate.
B People who are able to express themselves creatively in new situations have little incentive to acquire large vocabularies.
C The most eloquent people are people who have large vocabularies but also are able to express themselves creatively when the situation demands it.
D In educating people to be more eloquent, it would be futile to try to increase the size of their vocabularies.
E In unfamiliar situations, even people with large vocabularies often do not have specifically suitable words available.

Source: Crackverbal