Assertion $(X)$: Birds can consume food very quickly.
Reason $(Y)$: They possess a crop.

• A
  Reason $(Y)$ is incorrect for Assertion $(X)$.
• B
  Reason $(Y)$ is correct for Assertion $(X)$.
• C
  Both Assertion $(X)$ and Reason $(Y)$ are incorrect.
• D
  Assertion $(X)$ and Reason $(Y)$ are not consistent.