Answer:
B. cooling as the lava runs down the mountain
C. melting of rocks to form magma underground
Explanation:
Rocks are formed due to many process, in fact, all the choices mentioned lead to rock formation. However, for this case, at point R seems more of volcanic rocks and volcanic rocks are formed due to the cooling as the lava runs down the mountain and melting of rocks to form magma underground may lead to the final formation of rock.
