Assertion $(A)$: In group $15$ elements, nitrogen does not form pentahalides.
Reason $(R)$: Nitrogen can exhibit $+5$ oxidation state.
The correct option among the following is:

• A
  $(A)$ and $(R)$ are true. $(R)$ is the correct explanation of $(A)$
• B
  $(A)$ and $(R)$ are true, but $(R)$ is not the correct explanation of $(A)$
• C
  $(A)$ is true but $(R)$ is false
• D
  $(A)$ is false but $(R)$ is true