What is the difference between a visitor and a prospect?

What is the difference between a visitor and a prospect?
A . A prospect has an identified email address, while a visitor does not have an identified email address.
B . A prospect has an opportunity associated with it. while a visitor does not have an opportunity associated with it.
C . A prospect has submitted a Pardot form, while a visitor has not submitted a Pardot form.
D . A prospect has an assigned user, while a visitor does not have an assigned user.

Answer: C