Answer:
Swift uses understatement and irony when he says his plan is "a little bordering on cruelty" to highlight how cruel the plan really is.​
Explanation:
According to the excerpt from A Modest Proposal by Jonathan Swift, he talks about some people censuring a practice unjustly as it borders on cruelty and how he has always had the strongest objection to, no matter how well intended.
The statement that best explains Swift's use of rhetorical devices in this passage is his use of understatement and irony when he says his plan is "a little bordering on cruelty" to highlight how cruel the plan really is.​