Select all the primary causes of surface currents in the ocean 1.wind 2.gravity 3.earths rotation 4.extreme weather 5.density differences 6. uneven heating of oceans

The primary causes of surface current in the ocean are: WIND and DENSITY DIFFERENCES.
Ocean currents are caused by two types of factors, these are primary causes and secondary causes. The primary causes are responsible for originating the ocean current while the secondary factors determine the direction that the ocean current will travel. The primary causative agents are wind, density differences and uneven heating of the ocean while the earth rotation, uneven heating of the ocean and ocean bottom topography are secondary causative agent. 

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