Which of the following factors originates the oceanic currents?
A. Rotation of the earth
B. Revolution of the earth
C. Salinity difference in oceans
D. Density difference in oceans
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Question

Which of the following factors originates the oceanic currents? 
A. Rotation of the earth 
B. Revolution of the earth 
C. Salinity difference in oceans 
D. Density difference in oceans
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Accepted Answer

Option 2 (A, C, D) is the correct answer because:

*   **A. Rotation of the Earth:** The Earth's rotation causes the Coriolis effect, which deflects moving objects (including ocean currents) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection is a primary driver of the circular patterns (gyres) observed in ocean currents.

*   **C. Salinity Difference in Oceans:** Differences in salinity affect the density of seawater. Higher salinity water is denser. This density difference contributes to thermohaline circulation, a global system of currents driven by differences in temperature and salinity. Denser, saltier water sinks, while less dense, fresher water rises, creating currents.

*   **D. Density Difference in Oceans:** Density differences, primarily caused by variations in temperature and salinity, are a major driving force behind ocean currents. Cold, salty water is denser and sinks, while warm, less salty water is less dense and rises. This creates vertical movement of water, contributing to both surface and deep ocean currents.

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

*   **B. Revolution of the Earth:** The Earth's revolution around the sun primarily causes seasonal changes. While seasonal changes can indirectly influence ocean temperatures and thus density, the revolution itself is not a direct originator of ocean currents. The primary effect of revolution is on solar radiation distribution, not directly on water movement.

Therefore, only A, C, and D directly originate oceanic currents, making Option 2 the correct answer.