How does the misplaced modifier in “I wished for happiness at the fountain” create confusion? by making the order of events confusing to the reader
by suggesting that the person wanted happiness to be only at the fountain
by saying that there was no reason for the person to take longer than usual
by suggesting that the fountain wished the person happiness

Refute it, showing why it is mistaken—an apparent but not real problem; acknowledge its validity or plausibility, but suggest why on balance it's relatively less important or less likely than what you propose, and thus doesn't overturn it; concede its force and complicate your idea accordingly—restate your thesis in a more exact, qualified, or nuanced way that takes account of the objection, or start a new section in which you consider your topic in light of it. this will work if the counterargument concerns only an aspect of your argument; if it undermines your whole case, you need a new thesis.