Which of the following best describes the ongoing seasonal wind shift known as a monsoon?

The description of a monsoon is characterized by periodic reversals in wind direction, which is precisely what choice B states. Monsoons are not static; they are associated with seasonal changes that involve significant shifts in wind patterns. These shifts lead to contrasting wet and dry periods, typically associated with changes in temperature between the land and sea.

During the summer, for instance, land heats up more quickly than ocean water, causing winds to blow from the ocean towards the land, bringing moist air and precipitation. Conversely, during the winter months, land temperatures drop, and winds reverse, blowing from the land to the ocean, which results in drier conditions. This fundamental behavior of wind direction changing seasonally is what defines a monsoon.

The other options do not accurately describe a monsoon. A stable wind pattern that does not change is not characteristic of a monsoon, as the essence of a monsoon is its variability. A consistent dry season alone does not capture the dual nature of wet and dry periods inherent to a monsoon climate. Lastly, referring to a year-round effect overlooks the distinctive seasonal shifts that define the monsoon phenomenon.