Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Net dipole moment of a polar dielectric substance is zero in the absence of an external electric field.
Reason $(R)$: In the absence of an external electric field,the different permanent dipoles of a polar dielectric substance are oriented in random directions.
In the light of the above statements,choose the most appropriate answer from the options given below.

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