It’s true because your teacher says so
I’d say:
I had a hard time deciding whether to write an essay about the works of “Eudora Welty, Joan Didion, Gwendolyn Brooks” because the rest of the punctuations doesn’t make sense.
But actually it should be:
I had a hard time deciding whether to write an essay about the works of Eudora Welty, Joan Didion, and Gwendolyn Brooks.
(Without the quotation marks and inclusion the word “and” before “Gwendolyn”)
Answer:
The teenage son had a very messy room that hadn't been cleaned in ages.
Explanation:
An art song is usually for solo voice and is accompanied by solo piano. (Just as a side note, I recommend listening to the Erlking by Schubert if you have time; it's a German art song (lied))