Answer:
The correct option is: A. Troposphere
Explanation:
The temperature gradient is negative for the ocean. Thus, the temperature of the ocean gradually decreases from the surface up to a certain depth, this region is called thermocline, and then becomes constant.
Similarly, in the troposphere, the lowest layer of the atmosphere, the temperature gradient is negative. Thus, the temperature gradually decreases with height till the tropopause and then becomes constant on reaching the stratosphere.
Therefore, the temperature profile or the vertical gradient of temperature of the oceans is similar to that of the troposphere layer of the atmosphere.