Which of the following metamorphic rocks would most likely have formed at the highest temperatures and pressures

A. gneiss

B. schist

C. slate

D. phyllite

I think the correct answer from the choices listed above is option D. The metamorphic rock that would most likely have formed at the highest temperatures and pressures would be phyllite. It is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation.