The answer is density, temperature, and salinity. These are the factors that makes a current that is 50 meter less deep. The other choices will create a higher amplitude of the current.
Factors like "wind, temperature and salinity" interact to create currents that are less than 50 m deep.
<u>Explanation:</u>
Surface ocean currents are mainly governed by the wind system prevalent in that region.
As the surface ocean water interacts with the wind, it also does interact with the insolation received.
Water turns warmer or cooler depending on the intensity of insolation. Warmer waters bear the capacity to hold more salt. This makes warmer water a "good carrier of salinity" than cold water.
More the salinity more is the density of water. Dense water naturally sinks down giving rise to a convection current.
Thus the wind, temperature and salinity interact with each other to create shallow currents.
