Which of the Following Is True of the Preparation of the Metal

Multiple Choice

Which of the following is true of the preparation of the metal substructure for porcelain-bonded-to-metal crowns?

A) The metal substructure should have sharp angles.
B) The metal substructure must be concave in shape.
C) The metal substructure must be at least 1.5 mm thick.
D) To make room for the metal substructure and porcelain,these crowns require greater reduction of the tooth than all-metal crowns.