Hi! The answer to your question is really simple. Alfred Wegener proposed his theory of continental drift over the observation that the same fossil plans of mesosaurus were found in South America and Africa.
He asked, "why are the same species on different continents?", then he thought that it was because a large continent called Pangea split before.
Therefore, the answer is 1) Fossils in mesosaurus found in South America and Africa.
Cheers!
-10th Grader Snow.