Is one choice really an option?

I recently had a conversation with my youngest son and he said that he had do something and he gave only one choice. I thought about it and asked myself if one choice is really an option.
Technically, it is because the fall back option is always to do nothing, but in a practical sense one option is not really a choice.
It would be like asking someone to lunch and they give you a blank stare instead of an answer. Technically the blank stare is an answer, but you probably were looking for them to verbalize or shake their head yes or no.