"Highlight only" draws a dotted outline round the option to pick. Anything
that has no option to outline still shows in the question bar.
On WebAssign and Pearson Mastering, marks the option to pick - a
choice, a graph, or a dropdown - with a dotted outline in your Answer Color.
Turn it off and nothing is drawn on the page: answers appear only as text.
Uses the smarter model via /v1. Better at graphs and numeric answers. Off = 1 credit.