Question

I _____________ a single word he says.
A not believe

B do not believe

C am not believing

D will not believe​

Answer 1

I do not believe a single word he says

Explanation:

Affirmative: I believe in his words.

The Affirmative version of the given sentence do not contain an auxiliary verb. So, we have to use do or does ( present) to change it into negative or interrogative.

We can't use does as it is First Person Pronoun.

so the negative sentence would be

I don't believe a single word he says

Answer 2

Answer:

b. do not believe

Explanation:

b. is a correct answer