solidify at the surface of Earth. be eroded and deposited in layers. be formed from magma. change form when pressure is applied.
I gave my students this multiple choice question: In order for rocks to be classified as igneous, the rocks must

Only one answer is correct among these 4 choices:
- solidify at the surface of Earth.
- be eroded and deposited in layers.
- be formed from magma.
- change form when pressure is applied.

Could you tell me which one is correct?

be formed from magma.