Rocks are made of one or more minerals. Rocks are made of two or more elements. Rocks are made of magma and sediments. Rocks are made of sand changed by pressure.
I gave my students this multiple choice question: Students are comparing different rocks. What do all rocks have in common?

Only one answer is correct among these 4 choices:
- Rocks are made of one or more minerals.
- Rocks are made of two or more elements.
- Rocks are made of magma and sediments.
- Rocks are made of sand changed by pressure.

Could you tell me which one is correct?

Rocks are made of one or more minerals.