Question

what is an angle grinder used to grind? nonmetals only imperfections in wood hard, heavy materials soft, porous materials

Explanation:

An angle - grinder is a powerful tool used for cutting, grinding, and polishing hard, heavy materials like metals, concrete, and stone. It is not mainly for non - metals only, nor is it used for imperfections in wood (wood is usually worked with other tools) or soft, porous materials.

Answer:

C. hard, heavy materials