relatively thin layer of rock found above Earth's mantle relatively thin layer of water covering most of Earth's crust hot liquid rock located in Earth's outer core very dense rock located in Earth's inner core
I gave my students this multiple choice question: Earth's hydrosphere is best described as the

Only one answer is correct among these 4 choices:
- relatively thin layer of rock found above Earth's mantle
- relatively thin layer of water covering most of Earth's crust
- hot liquid rock located in Earth's outer core
- very dense rock located in Earth's inner core

Could you tell me which one is correct?

relatively thin layer of water covering most of Earth's crust