The answer is either B or D. Letter A doesn't make sense and letter C isn't right either because you need rainfall to have fertile plains.
Answer:
Ferrel Cell.
Explanation:
Ferrel cell is the circulating air that occurs between 30° and 60° or S of the equator. From 30° latitude to 60° latitude, a new cell is present which is known as the Ferrel Cell. This Ferrel cell produces prevailing westerly winds at the surface on these latitudes. Ferrel cell is a model for the wind circulation of mid-latitude segment of Earth which was proposed by William Ferrel in 1856.
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