Answer:
B. Air moves towards the poles as it cools
Step-by-step explanation:
The image represent convection cell or Hadley cell is a natural phenomenon in the atmosphere that occur due to difference in the density within a body of liquid or gas. These differences in density causes rise and fall in currents.
The process in step A refers to when hot air moves up and in the step B, the hot air encounters a cold surface, it direct exchange the heat with cold surface and the air cools down and move towards the poles.
Hence, the correct answer is "B. Air moves towards the poles as it cools".