Question

Which word in the sentence does the adverb modify?

The angry referee blew his red whistle often.

Answer 1

Angry describes the way he blew

Answer 2

That answer is incorrect. "Angry" describes the referee. "Often" describes his blowing. Therefore, "often" is the adverb modifying "blew"

Answer 3

@megsss333 is right.
But why is it in the BIO section?

Answer 4

blew is the answer.