user
Only two back bones and a thousand ribs.  What am I?
A: makes
B: hip pocket
C: railroad track
D: decalcification
E: anvil
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

C

<|end_of_solution|>