Answer:
A. gerund
Explanation:
The phrase in the question is a gerund phrase.
Gerund phrases are marked by verbs with the "ing" ending, and in general terms, they represent an action in course.
The pharse in the question starts with "By singing the song...", thus, it is a gerund phrase.
Answer:
The one about video games, the one about social media and the one about online learning.
