The correct answer is D. An underground deposit of minerals.
Step-by-step explanation
Metals are minerals, that is, they are natural substances that are normally in a solid-state. These resources are generally the product of physical-chemical processes that occur in the underground layers of the earth that transform different materials into these minerals. These minerals are obtained through mining, a process in which the earth's crust is broken until it reaches the place where these minerals are housed and in this way takes them to the surface to use them in the manufacture of different objects. Therefore, the correct answer is D. An underground deposit of minerals.