The main factors which produce the ocean currents are
A. Planetary winds
B. Variations in sea water temperature
C. Variations in sea water salinity
D. Revolution of the earth
Choose the correct answer:

Question

The main factors which produce the ocean currents are 
A. Planetary winds 
B. Variations in sea water temperature 
C. Variations in sea water salinity 
D. Revolution of the earth 
Choose the correct answer:

Accepted Answer

Option 1, "A, B and C are correct," is the correct answer because planetary winds, variations in sea water temperature, and variations in sea water salinity are all primary drivers of ocean currents. Let's break down why:

*   **A. Planetary Winds:** Winds blowing consistently across the ocean surface exert a frictional drag on the water. This drag forces the surface water to move, creating surface currents. The major wind belts, like the trade winds and westerlies, are directly responsible for driving major ocean currents like the Gulf Stream and the North Atlantic Current. The direction and strength of these winds directly influence the direction and speed of the currents.

*   **B. Variations in Sea Water Temperature:** Temperature differences in seawater create density differences. Warm water is less dense than cold water. This density difference leads to convection currents. Warm water rises, and cold water sinks. This vertical movement contributes to the overall circulation pattern of the ocean. This process is a key component of thermohaline circulation.

*   **C. Variations in Sea Water Salinity:** Salinity also affects water density. Saltier water is denser than less salty water. Areas with high evaporation rates or ice formation have higher salinity, leading to denser water that sinks. This sinking contributes to the thermohaline circulation, a global system of currents driven by density differences.

Now, let's explain why the other options are incorrect:

*   **Option 2: A, B, C and D are correct.** While A, B, and C are correct, D (Revolution of the earth) is not a *direct* primary factor in producing ocean currents. The Earth's rotation causes the Coriolis effect, which *deflects* existing currents (and winds). It doesn't *create* the currents in the first place. The Coriolis effect influences the *direction* of currents, but the currents themselves are initiated by wind, temperature, and salinity differences. Therefore, including D makes this option incorrect.

*   **Option 3: A, B and D are correct.** As explained above, while A and B are correct, D (Revolution of the earth) only influences the direction of currents through the Coriolis effect, not their initial creation. Therefore, this option is incorrect.

*   **Option 4: Only A and B are correct.** This option is incorrect because C (Variations in sea water salinity) is also a significant factor in creating ocean currents, particularly through its influence on water density and the thermohaline circulation.

In conclusion, Option 1 is the only correct answer because it accurately identifies the three primary factors that directly produce ocean currents: planetary winds, variations in sea water temperature, and variations in sea water salinity.