Which of the following is an example of a theory?

Gravity

1+1=2

Evolution

An example of a theory is Evolution, we don't really know 100% how we came to be as we are now, but we do know that 1+1=2 as a fact, same with gravity, we Know it exists because it's what ties us to earth and we can "feel" it, but not Evolution, Evolution is a theory, just like the BingBang