Answer:
C. Recording the spread of the seafloor in the mid-Atlantic region
Step-by-step explanation:
This seems to be the only logical answer. Since we are talking about a method in studying plate tectonics/movements, using evidence of it, seafloor spreading, would be the best idea out of the four.
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other.
Hope this helped! :-)