In context, which is the best version of the underlined portion of sentence 11 (reproduced below)?
K-Pop artists will also often infuse phrases in other languages, especially English phrases, into his lyrics to add to the music's appeal across the globe.

This answer is correct because “their” is the correct pronoun to use in order to refer to the antecedent “K-Pop artists.” The antecedent is plural and gender non-specific, so it needs a plural, gender non-specific pronoun. Answer phrases into his lyrics to add might be tempting if you’re not paying attention to the whole sentence. The comma in the beginning of the underlined portion completes a parenthesis, and is therefore necessary.