igneous rock becoming sedimentary rock. igneous rock becoming metamorphic rock. metamorphic rock becoming igneous rock. sedimentary rock becoming metamorphic rock.
I gave my students this multiple choice question: The part of the rock cycle that transforms compressed rock formed from sea organism shells into a harder, denser rock is

Only one answer is correct among these 4 choices:
- igneous rock becoming sedimentary rock.
- igneous rock becoming metamorphic rock.
- metamorphic rock becoming igneous rock.
- sedimentary rock becoming metamorphic rock.

Could you tell me which one is correct?

sedimentary rock becoming metamorphic rock.