Question

How does the authors purpose affect his or her rhetorical choices

Answer 1

Think about how his choices might be different if his purpose were just to inform. His language probably wouldn't be quite so fiery or his tone so urgent. An author's word choice is always purposeful and full of thought. When you identify his purpose, it's easy to pick out what he chose certain images or words in his writing.

Answer 2

Rhetorical choices is another way of saying language choices, so what you're asking is how does that author's purpose impact the language in the text.