What creature walks on four legs at dawn, two legs in the day, and three legs at sunset?

The correct answer is D. A man.

This riddle refers to the stages of a person’s life. In the morning (dawn) of life, a baby crawls on all fours (four legs). During the day (adulthood), a person walks on two legs. In the evening (sunset) of life, an elderly person might use a cane for support, which is represented as a third leg.