Answer:
a. Wind is the major cause of surface ocean current
b. Thermohaline circulation is the major cause of deep ocean current
Step-by-step explanation:
Ocean currents is said to be the redistribution or movement of water bodies from one point to another.
On a wide scale the major forces or causes behind the ocean current on the surface is wind-driven. The ocean water on the surface and the atmosphere is directly heated by the sun and it produces winds which blows over the ocean surface , transmitting energy through the process resulting to waves and current.
On the other hand the major causes of deep ocean currents is the Thermohaline circulation . This exist due to temperature and salinity(salty) variation . Usually, water having lower temperature (cold) and high salinity content possesses higher density than high temperature (warm) and low salinity content water respectively. The higher density water sinks deeper. The density variation is the major driving force behind deep ocean current in an extensive scale. And this is what we call the Thermohaline circulation.