How is the edge of a highlight often treated on a glossy object sketch?

Correct answer: Small and sharp

The governing concept is material rendering through reflected light. A glossy surface reflects a relatively concentrated image of the light source, so its brightest highlight is often limited in area and has a distinct, sharper edge than the surrounding tones. Thus A is the best answer. A very broad, uniform mark is more likely to flatten the form; an invisible highlight removes an important surface cue, and gloss does not always produce a grainy edge. The exact softness can still vary with curvature and the size of the light source.