The legal holidays in China belong to the 24 solar terms.

The 24 solar terms in China are: slight cold, severe cold, beginning of spring, rain, fright, vernal equinox, Qingming, Grain Rain, long summer, xiaoman, mang, summer solstice, slight summer heat, great summer heat, beginning of autumn, early summer heat, white dew, autumn equinox, cold dew, early frost, beginning of winter, light snow, heavy snow and winter solstice; So option a fits the question.

So choose: a.