Final answer:
True, each sculpture had to make a relief in marble, as per the contest rules involving marble as a favored medium for classical sculptures, including reliefs.
Step-by-step explanation:
The statement that each sculpture had to make a relief in marble appears to be consistent with the rules of a sculpting contest or a set of guidelines given the information provided about the use and carving of marble in classical sculpture. It can be affirmed as True based on the reference that emphasizes marble as a preferred medium, especially in the context of classical Greek art, where carving statues and reliefs in marble was a common practice. Carvers utilized various tools to shape the marble, starting with larger tools for broad strokes and moving to finer chisels and drills. Marble sculptures often depicted figures in contrapposto position to give a more naturalistic pose. The process also included using a maquette for planning the sculpture before carving the larger piece. Furthermore, there is a mention that artists like Michelangelo would directly carve into marble to release the form within. The reference to Greek artists' preference for bronze over marble, with marble copies made predominantly by the Romans, does not detract from the fact that marble was still commonly used for sculpting, including relief work.