The relationship between shadow length and solar terms

The answer? Yes (d), because Xiaoxing is in the northern hemisphere, on the winter solstice? When the height angle of the sun is relatively small, as shown in the figure, the height angle of the sun is smaller from winter to the sun, so the shadow is longer. Relationship with the revolution of the sun: With the revolution of the earth, the direct point of the sun moves between the tropic of cancer, resulting in different solar altitude angles and different shadow lengths. If you add "morning" to this question, the answer is still the same, but if you say the same pole, is it morning or afternoon? The shadow is the longest, so it is in the morning, because the sun just rises in the morning and the height angle of the sun is small.