Answer:
They have a gizzard to grind the food.
Explanation:
Birds cannot chew since they have no teeth. However, the beak allows them to split very large seeds or swallow them directly.
For their digestion they have a stomach where digestion enzymes are released. Also they have a gizzard that is an organ that grinds the food mechanically. This gizzard usually has small stones inside that were previously ingested and that helps to digest the food.
I'd say A: tidal waves. B, C, and D don't really seem to fit for me.
The answer is B , because your stress decreasing can not cause a disorder
