In the oceans the colder water sinks into deep basins while warmer water stays closer to the surface the water then moves around in the ocean basin. this causes a. tidal waves
b. wind drifts
c. ocean currents
d. plate tectonics

Explanation:

An ocean current is water movement in the seas, which depends on gravity, Coriolis Effect and density.

Specifically, cold water has higher density than warm water, that's why the wamer water stays closer to the surface and the cloder water sinks into deep basins. According to physics, the less dense fluid is the one that floates over the more dense fluid.

So, this water movement combined with the wind-driven flow of warm water creates patterns of ocean currents in around the globe.

Therefore, the right answer here is C. Ocean Currents.

d) a constitutional amendment