user
I walk on Four legges in the morning, two legs in the afternoon, and three legs in the evening.   what am i?
A: human
B: cot
C: vertebra
D: use
E: good day
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

A

<|end_of_solution|>