Suppose an author's intent is to teach a moral lesson. Why would he use allegory?

Returning from vietnam, we were indeed given a parade. crowds of screaming people waving signs — not just on one road, one day. no, they were everywhere. every day. on the streets, on the television, on the radio. a hot, angry tangle of shaking fists and ugly words that threatened us like a monster with a hundred heads. our country had chewed us up and spit us out, and now we were being treated as if it were our fault. what is one way the author's use of language contributes to the tone of this passage? a. the use of figurative language creates a feeling of resentment. b. the phrase "hot, angry tangle" is used sarcastically to create irony. c. the word "parade" is used sarcastically to create a lighthearted mood. d. the parallelism draws attention to the confusion of those returning.