The Perception of Speech Is Made Easier by All of the Following

The perception of speech is made easier by all of the following EXCEPT that

A) there is impressively little variation from one speaker to the next.
B) the content of the speech we hear is often predictable on the basis of knowledge external to language.
C) the content of the speech we hear is often predictable because of the rules guiding which sounds go together.
D) most of the speech we hear employs a relatively small number of words,used over and over again.