Metamorphic rock is formed by:

• A. Erosion and deposition
• B. Weathering
• C. Heat and pressure acting on any type of rock
• D. Cooling of molten rock

Answer: (C)

Metamorphic rocks come from rocks that are transformed by high heat and pressure deep in the Earth's crust, while remaining in solid form. The intense heat and pressure rearrange minerals and grow new textures without melting, so the rock changes its mineral makeup and structure but stays solid. This process can happen to any original rock type and often results in features like foliation, where minerals line up in layers due to directional stress, producing rocks such as slate, schist, or gneiss. It’s the solid-state transformation under heat and pressure that sets metamorphic rocks apart from other types: if rock melts, it becomes igneous; if it’s broken down and redeposited, it becomes sedimentary.