user
I build up castles.    I tear down mountains.    I make some men blind,   I help others to see.    What am I?
A: sand
B: feature
C: snowman
D: black
E: black man
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

A

<|end_of_solution|>