Why was the Mesosaurus fossil one of the most convincing arguments in favor of continental drift?

Question

a
The fossils of the Mesosaurus were found in both South American and South Africa, whose continents lined up to look like they were together at some point in the past
b
The Mesosaurus was a water dwelling dinosaur whose fossils were found in land locked regions of the continents
c
The Mesosaurus fossils were found on the tops of mountains, which means they must have been risen up through tectonic activity
d
The fossils of the Mesosaurus were found in a rock layer that was older than the Mesosaurus itself

Answer 1

a
The fossils of the Mesosaurus were found in both South American and South Africa, whose continents lined up to look like they were together at some point in the past.