They need it to grow healthy
The best answer is D, birds.
For more information and details on the way a bird's respiratory system works:
https://asknature.org/strategy/air-flow-patterns-facilitate-efficient-gas-exchange/
Gulls, crows and herons are all opportunists. They'll eat just about anything that they can get their beaks on. That includes fiddler crabs.
Adjustment knobs are used to focus light in a light microscope
