The correct answer is 'Adverb'. Key Points - Here, in the given above sentence the underlined part "over" is used as an adverb. - As per the general rule, an adverb is a word that modifies a verb, an adjective, another adverb, or even a whole sentence. - Example: - I've been chewing the problem over since last week. - We put a collar around its neck. - Here, in the given above examples, 'since and around' can be used as an adverb. - According to the explanation and example that are given above, 'Adverb' is the correct part of speech for the given above sentence.