Respuesta :
Answer:
The rock with the highest metamorphic grade would be the one that is formed at '1,200 °C' and '20 kilobars of pressure'.
Explanation:
- When it comes to the metamorphic grade of rock, it is clear that higher the heat and pressure the rock is subjected to, higher would be its metamorphic grade.
- Rocks with a high metamorphic grade are comparatively easy to identify because such rocks exhibit foliated surface. Gneiss is a "metamorphic rock" with the "highest metamorphic grade".