Multiple choice problem

Qingming is one of the 24 solar terms in China. Because the 24 solar terms objectively reflect the changes of temperature, rainfall and phenology throughout the year, ancient working people used them to arrange agricultural activities. Huainanzi? Astronomical training says: "On the 15th day after the vernal equinox, the bucket refers to B, and the Qingming wind is coming." According to the centenarian question, "everything grows clean and bright at this time." So it's called Qingming. "As soon as Qingming arrives, the temperature rises and the rainfall increases, which is a good time for spring ploughing and spring planting. Therefore, there is an agricultural proverb that "before and after Qingming, point melons and plant beans" and "planting trees is not as good as Qingming". It can be seen that this solar term is closely related to agricultural production.