Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$: Late wood has fewer xylary elements with narrow vessels.
Reason $R$: Cambium is less active in winters.
In the light of the above statements,choose the correct answer from the options given below:

• A
  $A$ is false but $R$ is true
• B
  Both $A$ and $R$ are true and $R$ is the correct explanation of $A$
• C
  Both $A$ and $R$ are true but $R$ is $NOT$ the correct explanation of $A$
• D
  $A$ is true but $R$ is false