a sea floor a windblown desert a site deep underground a site covered by a glacier
I gave my students this multiple choice question: Which of the following areas is most likely to form metamorphic rocks such as gneiss and schist?

Only one answer is correct among these 4 choices:
- a sea floor
- a windblown desert
- a site deep underground
- a site covered by a glacier

Could you tell me which one is correct?

a site deep underground