Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: $FSH$,which interacts with membrane-bound receptors,does not enter the target cell.
Reason $(R)$: Binding of $FSH$ to its receptors generates a second messenger (cyclic $AMP$) for its biochemical and physiological responses.
In the light of the above statements,choose the most appropriate answer from the options given below:

• A
  Both $(A)$ and $(R)$ are correct and $(R)$ is the correct explanation of $(A)$
• B
  Both $(A)$ and $(R)$ are correct but $(R)$ is not the correct explanation of $(A)$
• C
  $(A)$ is correct but $(R)$ is not correct
• D
  $(A)$ is not correct but $(R)$ is correct