What type of rock does preexisting rock become

Metamorphic rock is a type of rock that the preexisting rock becomes a new rock.
Metamorphism has also different types; the Contact metamorphism and the regional metamorphism. Contact metamorphism happens when magma is mixed with the solid rocks in the surroundings. For example when magma is starting to form igneous rock, it may increase that probability that it will reach the country’s rock and that’s affected the current formation of the rock. Regional metamorphism is also called as dynamic metamorphism. This happens when the pressure from underground makes the rock from above move and change into new rock formation

Answer (b) supersaturation;