What was the answer to the riddle the sphinx asked oedipus and why?

Human being, because a human being walks on all fours in early life, on two legs as an adult and with a walking stick in old age. I hope this helps you.

What is the creature that walks on 4 legs in the morning, 2 legs in the noon, and 3 in the evening. And he answered "Man", because when man is a baby it crawls on all 4s and when young and in its prime it walks with its 2 legs and when man is old it uses a cane as a 3rd leg