One option for including irony in a poem is to use:
allegory
allusion
litotes
oxymoron
is it oxymoron?

The correct answer is C. Litotes

Explanation:

The irony is a literary and rhetorical device used to create humor by using certain words to express a meaning that is opposite to what is expected in terms of literal meaning or situations. This means irony relies on the incongruence between the language use and the real meaning or the expected outcomes in a situation and the real outcomes.

This literary device can be used in poems, novels and other literary works through simile, sarcasm or litotes, which is figure of speech in which something affirmative is stated by denying the opposite statement which means the litotes is a type of irony that relies in an incongruence of what is being said and what is being mean. Additionally, litotes are part of figurative language which made them especially suitable for poems rather than verse. Thus, the best option for including irony in a poem is litotes as this figure of speech rely on the incongruence between language and meaning which is the main purpose of irony. Also, this figure of speech is suitable for poems and is the only one that is used to express irony.