Surface currents are caused by friction between which two elements?
a. the ocean surface and wind
b. warm air fronts and cold air fronts
c. the ocean surface and deep ocean waters
d. northern currents and southern currents

A.) The ocean surface and wind

Surface currents are caused by friction between the ocean surface and wind.

Ocean current is the horizontal movement of seawater on the ocean's surface. It is driven by the wind's circulation above the ocean's surface. Frictional stress found between the ocean's surface and the circulating wind causes the water to move at the direction of the wind.  

Ithink d would be correct