In order of the questions, the answers are D,C,C,C,A,B,C,D,A,C,C,B,D. the main problems were that there were missing prepositions, a lack of pluralizing nouns, and incorrect verb tenses.
Answer:
The correct answer is A) The singer, who was very talented, knew the words to the song.
Explanation:
The clause "who was very talented" is considered to be nonessential for two reasons: 1) it acts as an adjective to the subject "singer", yet, if it were removed, the meaning of the sentence would remain unaltered. 2) it is between commas.