Final answer:
The four agents that drive metamorphism are heat, pressure, chemically reactive fluids, and combinations of these three parameters.
Step-by-step explanation:
The four agents that drive metamorphism are heat, pressure, chemically reactive fluids, and combinations of these three parameters. Heat causes minerals to soften and allows ions to migrate, while pressure reorients minerals, creating a noticeable feature called foliation. Chemically reactive fluids can also alter the composition of rocks. The type of metamorphic rock formed depends on the rock's initial composition and the specific agents of change involved.