题目1单选题
Why is the Chinese Farmers' Harvest Festival set on the Autumnal EquinoxA. The Autumnal Equinox is one of the 24 solar terms, and most crops ripe in autumnB. The Autumnal Equinox is the most important of the 24 solar termsC. The Autumnal Equinox has been observed by Chinese people for over 2,000yearsD. A dozen of ethnic groups in China celebrate their harvest on the Autumnal Equinox