Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ $A$ pendulum clock when taken to Mount Everest becomes fast.
Reason $R:$ The value of $g$ (acceleration due to gravity) is less at Mount Everest than its value on the surface of earth.
In the light of the above statements,choose the most appropriate answer from the options given below.

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