A. Participle
The underline word in the sentence, the boiled egg smelled rotten but tasted great! Which is boiled is a participle and not a verb because it doesn’t rely an action in the sentence instead it relays a modification or a description to the egg like an adjective or an adverb which is boiled egg. Participle is technically a verb that is utilized to describe a noun, noun phrase, verb or verb phrase.