user
I'm hiding in the air,  I'm hiding everywhere.   Under your bed,  In your cupboard,  I'm hiding everywhere.    What am I?
A: blimps
B: supply
C: ventilation system
D: oxygen
E: mystique
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

D

<|end_of_solution|>