Answer:
The correct answer is option A. "a mineral or metal with economic usefulness".
Step-by-step explanation:
An ore is defined as a rock or sediment found in nature which contains a mineral or metal with economic usefulness. The minerals or metals in the ore must be extracted before they could be used, and typically, they are refined via smelting. The ore grade is defined according to the concentration of the mineral or metal beneath the rock or sediment.