Question

question 14
the ekman spiral is caused by:
the wind and the coriolis effect.
density differences in the water column.
pressure gradients.
the pycnocline.
the wind and gravity.

Explanation:

The Ekman spiral is a phenomenon in oceanography. It occurs due to the interaction between wind stress on the ocean surface and the Coriolis effect (which is related to the rotation of the Earth). Wind drives the surface water, and the Coriolis effect causes subsequent layers of water to move at angles to the layer above. Density differences in the water column are related to thermohaline circulation, pressure gradients are more about general fluid flow (not specific to the Ekman spiral mechanism), the pycnocline is a layer of rapid density change (not the cause of the spiral), and gravity - while important in general ocean dynamics - is not the key factor along with wind for the Ekman spiral as the Coriolis effect is.

Answer:

the wind and the Coriolis effect.