riddle - if you have one, you have none

If you have three, you have three. If you have two, you have two. If you have one, you have none. What is it?

Answer

This is kind of a play on words, but:

Options
If you have 3 options, you have 3 options. If you have 2 options you have 2 options. If you have only 1 option, you don't have any options.

Along similar lines, this works too:

Choices
If you have 3 choices, you have 3 choices. If you have 2 choices you have 2 choices. If you have only 1 choice, you don't have a choice.