Final answer:
Metamorphic rock formation is best described by the process where pressure causes an existing rock to change, especially in environments with high temperature and pressure or tectonic activity.
Step-by-step explanation:
The correct answer that describes metamorphic rock formation is: c) Pressure causes rock to change. Metamorphic rocks are formed from pre-existing rocks that undergo alteration due to significant heat and/or pressure. This change often occurs in environments such as beneath the Earth's surface where temperature and pressure are high or in areas with intense tectonic activity such as mountain belts. A metamorphic rock's characteristics, including any foliation or banding in the structure, depend on the original composition of the protolith or the parent rock and the conditions of metamorphism.