The compound of a metal found in nature is called:

Correct option is B

The compound of a metal found in nature is called mineral.
Physical Properties of Minerals 
1. Hardness: Resistance to scratching.
2. Colour: Caused by electromagnetic radiation interaction with electrons.
3. Lustre: Reflection of light from the mineral surface.
4. Specific Gravity: Density of mineral.
· Flux: A flux is a substance that is added to the charge in a furnace to remove the gangue.
· Gangue: Earthly impurities including silica, mud etc., associated with the ore are called gangue.
· Slag: It is the fusible product formed when flux reacts with impurities during the extraction of metals
· Ore is a deposit in Earth's crust of one or more valuable minerals.