Question

Identify the choice that best describes the underlined verb.
Bowling is the top participation sport in the U.S. today, with 53 million players.

gerund
present participle
participial phrase
infinitive

Answer 1

I'm assuming that the underlined verb is bowling.
If that is the case, then the answer would be gerund.
Gerund is a verb form that functions as a noun in a sentence. As you can see here, bowling is used as the subject of the sentence.
Although present participle looks the same, it is used as an adjective, not a noun in a sentence. Since bowling is not a participle, it cannot be a participial phrase. Infinitive has the following form: to + verb.