What explains the eastward flow of the equatorial counter-current?

1. The equatorial counter-current flows eastward in a zone between the westward flowing North Equatorial Current (NEC) and the South Equatorial Current (SEC). 2. The westward flow of the NEC and SEC, primarily driven by trade winds, causes a pile-up of surface water on the western side of ocean basins. 3. This convergence (Option B) and subsequent accumulation of water creates a pressure gradient, with the sea surface being higher in the west than in the east near the equator. 4. The water then flows eastward down this pressure gradient, resulting in the equatorial counter-current. 5. Option (A) is incorrect; the Earth's rotation influences the direction of currents (Coriolis effect) but is not the primary cause of the counter-current's existence. 6. Option (C) is incorrect; while salinity differences affect water density and deep ocean circulation, they are not the main driver for this surface current. 7. Option (D) is incorrect; the belt of calm (Doldrums) near the equator has weaker winds, which *allows* the counter-current to flow more easily against the general westward wind drift, but it doesn't cause the pressure gradient that drives the flow.