Answer:
a. they were carved on flat surfaces like tomb and palace walls and columns.
Explanation:
Reliefs carved on the stone walls of the buildings were usual in ancient Egypt, Mesopotamia, and various Middle Eastern relief cultures. The Egyptians showed cautiously modeled figures erecting from the ground generally in low relief. They showed figures standing sideways which contained within a sharply engraved outline. Such high respites first became popular in ancient Greece. Attic tomb reliefs showed specific figures or personal groups from the fourth century BCE. They used the sculptured friezes to decorate the Parthenon and various classical temples. The Roman tombs were prominent for art relief sculptures during the period of second and third centuries CE.
