There are two types of ocean currents: deep currents and surface currents. Which of the following is the best explanation for why oceans have two different types of currents? A. Surface currents are caused by wind whereas deep currents are caused by differences in density.

B. Surface currents are caused by differences in density whereas deep currents are caused by wind.

C. Surface currents are caused by temperature differences whereas deep currents are caused by changes in salinity.

D. Surface currents are caused by changes in salinity whereas deep currents are caused by changes in temperature.