Final answer:
Bronze was often used instead of marble in ancient Greek sculpture due to its value and recyclability. This resulted in few surviving bronze sculptures and the need to rely on Roman copies in marble for understanding Greek art.
Step-by-step explanation:
Bronze was often used instead of marble in ancient Greek sculpture because bronze is valuable and can be melted down and reused. This led to many bronze sculptures being recast into weapons or other objects, resulting in few surviving original bronze sculptures. As a result, we often rely on ancient Roman copies in marble to understand the artistic achievements of the Greeks.