user
what is going up and down at the same time but never moves from where it is standing?
A: clock
B: stairs
C: drive
D: lodge
E: place
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

B

<|end_of_solution|>