Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ In a particular point defect,an ionic solid is electrically neutral,even if few of its cations are missing from its unit cells.
Reason $(R):$ In an ionic solid,Frenkel defect arises due to dislocation of cation from its lattice site to interstitial site,maintaining overall electrical neutrality.
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
  $(A)$ is correct but $(R)$ is not correct
• C
  $(A)$ is not correct but $(R)$ is correct
• D
  Both $(A)$ and $(R)$ are correct and $(R)$ is the correct explanation of $(A)$