Carbon forms crystal structures under certain conditions. Carbon can exist as a solid, liquid, or gas. Carbon bonds in many ways with itself to form chains. Carbon exists in radioactive forms.
I gave my students this multiple choice question: What characteristic of carbon [C] makes it essential to living organisms?

Only one answer is correct among these 4 choices:
- Carbon forms crystal structures under certain conditions.
- Carbon can exist as a solid, liquid, or gas.
- Carbon bonds in many ways with itself to form chains.
- Carbon exists in radioactive forms.

Could you tell me which one is correct?

Carbon bonds in many ways with itself to form chains.