Answer:
If it´s not A then choose C
Explanation
If they were land animal and could not swim then the only logical reasoning would be that the two pieces of land drifted apart from each other and the fossils were in between them and that´s why they ended up in the ocean.
The hear makes sure that oxygen taken in by the lungs gets to the brain.
They are able to respond to the presence of invading organisms because they recognize the<u> antigen </u>on the surface of organisms. There are specific receptors on the surface of immune system cells.