Question

which substance is a metal found in earth’s crust and formerly used in the production of paint?

cobalt

lead

asbestos

copper

Explanation:

Cobalt is used in some pigments but not as widely in general paint production historically. Asbestos is a fibrous mineral, not a metal, and was used for fire resistance, not paint base. Copper is a metal but not a primary historical paint ingredient. Lead, a metal abundant in Earth's crust, was commonly used in lead-based paints for durability and color retention before being banned due to toxicity.

Answer:

lead