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 am hesitating between 4 options to answer the following question, which option should I choose?
Question: What characteristic of carbon [C] makes it essential to living organisms?
Possibilities:
- 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.

Carbon bonds in many ways with itself to form chains.