Final answer:
The density of a mineral is affected by the cooling rate of molten materials.
Step-by-step explanation:
The property of a mineral that is affected by the cooling rate of molten materials is c) Density.
When molten materials cool at different rates, it can result in varying densities of the minerals formed. A slower cooling rate allows more time for the atomic arrangement to settle into a dense crystalline structure, leading to a higher density. On the other hand, faster cooling rates may result in a less dense arrangement and lower density.