What punctuation mark should be used before the choices when asking a question starting with "which"?

In the following question:

Which is more expensive_ the apple or the orange?

What punctuation should I use in place of the underscore?

I have thought of a few possibilities.

Which is more expensive? The apple or the orange?

When I read it without punctuation, I kinda raise my tone in both "expensive" and "orange", so I guess I should put question marks in both places?

Which is more expensive, the apple or the orange?

The two parts belong to a single question, so there should be a single question mark at the end?

Which is more expensive - the apple or the orange?

I faintly remember that I saw something like this in books. My memory could be wrong though.

Which should be used and why?