a) is incorrect because the speaker says we only tend to think of people who speak more than one language as being “bright”, not that they actually are brighter.
b) is incorrect because the speaker says they often find one language more suitable than another for expressing certain kinds of thoughts and feelings, not that they have difficulty expressing emotions.
c) is incorrect because the writer refers to mental exercise, not physical exercise.
d) is incorrect because the idea of having a split personality is mentioned, not the idea of having an attractive personality.
e) is correct because the speaker says: And it’s true that we tend to think of people who can speak two or more languages as being bright.