Twenty-four solar terms are an important basis for working people in ancient China to engage in agricultural production activities, and the cycle of the twenty-four solar terms is ().

Twenty-four solar terms are defined according to the position of the earth in its orbit around the sun. Starting from the longitude of the vernal equinox, every time the sun runs 15 on the ecliptic, it becomes a solar term. The time of each solar term is about half a month apart, and it is listed in twelve months respectively. The twenty-four solar terms are about a tropical year (365.2422 days). So choose B.