For a veneer preparation, the most appropriate margin design at the INCISAL edge (when incisal overlap is done) is:

Correct answer: A. Shoulder (butt joint)

• A. Correct (keyed). For an incisal-overlap veneer, a shoulder/butt-joint at the incisal provides a defined seat and resists shear.
• B. A chamfer is the typical GINGIVAL/facial veneer margin, not the incisal overlap.
• C. A feather edge is too thin/unsupported for porcelain.
• D. A long bevel can create a thin unsupported lip of porcelain and is generally avoided incisally.

Note: Margin choice varies by veneer type (window vs. incisal-overlap). The keyed answer for the incisal overlap is a shoulder/butt joint; gingival/facial margins are usually a light chamfer.