Answer:
b. may happen as regression brings rock closer to the Earth's surface.
Step-by-step explanation:
The term metamorphism when applied to geology refers to the changes that occur between rocks that allow them to form into different rocks over a cycle. Within this process, there is a type of metamorphism known as retrograde metamorphism, which occurs when there is a regression that brings rocks close to the surface and promotes a decrease in temperature and pressure.