Question

Which idea supports the studies of magnetic reversals in rocks under the sea?

Answer 1

I would say the topic of such a study would be paleomagnetism and perhaps its effect on plate tectonics because when the seafloor spreads at the mid-ocean ridges, magnetized stripes of rock, symmetrical on either side of the trench form and they record changes in the earth's magnetic poles at certain times so can be dated to help show the rate of spreading of the seafloor at these locations.

Answer 2

Seafloor spreading.  
This is a procedure that happens at mid-sea edges. These edges check the limits between two plates that are wandering, or moving far from each other. As the plates move separated, the outside layer is focused and debilitated. This permits magma from under the surface to separate through the outside layer, turning out and making new ocean bottom. The plates move separated, conveying the "new" ocean bottom with it.