Question

Choose the correct form of the pronoun in parentheses.

(Whoever, Whomever) draws the best picture will win a prize.

Answer 1

Rephrase the sentence:

Who draws the best picture?
He draws the best picture.

Now, you need to use this:
He = whoever
Him = whomever

We will have to use whoever.

Whoever draws the best picture will win a prize.