The word "option" means "choice". You can use it when you're talking about making a decision:
A: Where should we go?
B: I don't know. What are our options?
A: Why did you do that?
B: Because I had no other option!
"Option" is just a tiny bit more formal than "choice". For most situations, you can use either word. But there are some collocations that usually use "option" instead of "choice":