The error in subject-verb agreement is Joe and his friends prefers
I'm assuming that the underlined word is answer and i think its transitive. but i'm not completely sure.
Answer:
the way the author would convey central idea of the article is by title by the gist(and some times the have a sumaray of text look at that to if there )
Explanation:
Yes, one should make sure that the subjects and verbs agree
