What is the source of energy that causes surface currents in the ocean? a. density differences between freshwater and seawater b. the magnetic attraction between the north and south poles c. the gravitational pull of the moon and the sun on the ocean d. winds created by the uneven heating of air on earth by the sun

TBH I think the answer is B I am not really sure but it kinda sounds like it by reading this
Energy in the Ocean and Atmosphere. ... Wind-driven and ocean-current circulations move warm water toward the poles and colder water toward the equator. The ocean can store much more heat than the land surfaces on the Earth. The majority of the thermal energy at the Earth's surface is stored in the ocean.
I really hope this helps and I hope I gave you the right answer.