An adverb is an adjective + a verb. Meaning, it's a word that describes what someone/something is doing during the action.
A (whistle) & C (referee) are both nouns - person, place, or thing.
D (red) is just an adjective - describing something
B would make the most sense, it's telling you what the referee does with his whistle.
Hope this helped!
I think the correct answer is "Examples" but you should give me the answer choices so i can be more sure.
