Which of the following best describes the formation process of rocks involved in regional metamorphism?

The formation process of rocks involved in regional metamorphism is best described as occurring under high heat and pressure. Regional metamorphism typically occurs over large areas and is usually associated with tectonic forces such as continental collisions or mountain-building activities. In these scenarios, existing rocks—whether igneous, sedimentary, or older metamorphic rocks—are subjected to significant increases in temperature and pressure over an extended period. This leads to profound physical and chemical changes in the rock, resulting in the formation of metamorphic rocks.

For instance, the increased pressure can cause minerals to realign and recrystallize, while the high temperature can drive metamorphic reactions that change one mineral into another. This process is distinct from other types of rock formation, which may involve sedimentation, volcanic activity, or crystallization from magma, each of which represents different geological processes not characterized by the heat and pressure conditions typical of regional metamorphism.