Correct Option (b):
The Indian Ocean is unique among major oceans due to the distinct seasonal reversal of its surface ocean currents. This phenomenon is primarily driven by the seasonal changes in wind direction associated with the monsoon system, leading to what is known as the monsoon drift.
During the Southwest Monsoon season (typically June to September), strong southwesterly winds push the surface currents predominantly eastward. Conversely, during the Northeast Monsoon season (typically November to February), the wind direction reverses to northeasterly, causing the surface currents to flow westward. This direct influence of seasonally reversing winds is the fundamental factor responsible for the change in the regular direction of ocean currents in the Indian Ocean.
Incorrect Options:
The Indian Ocean is bounded by landmasses to its north, which influences its overall circulation pattern. However, this geographical characteristic alone does not directly cause the seasonal reversal of surface currents.
The Indian Ocean is not a land-locked ocean. It is widely open to the Southern Ocean in the south, facilitating significant water exchange with other global oceans.
While variations in salinity exist within the Indian Ocean and contribute to density-driven currents (thermohaline circulation), these differences are not the primary cause for the large-scale, seasonal directional reversal of surface currents. This reversal is predominantly a wind-driven phenomenon linked to the monsoon system.