(With pictures) There is a certain regularity in the time distribution during the two days when sunlight enters the end of the tunnel. Which solar term is symmetrical?

First of all, I want to know if the second question is B. .

First: A's problem is that the sun shines in the morning, and the trajectory of the sun rises in the south and sets in the west. The sun is in the southeast in the morning, so the tunnel entrance should face the sun, that is, the southeast.

Third: the reason of C I guess the second topic is B, because Changxia is a symmetrical point, and there are 3.4.5.6.7.8.9,6 between February and 10, which coincides with Changxia's inference, so April takes June as a symmetrical point, which just corresponds to August.

These are my personal thoughts.