Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A) : Refractive index of glass is higher than that of air.
Reason ( \(\mathrm{R}\)) : Optical density of a medium is directly proportionate to its mass density which results in a proportionate refractive index.
In the light of the above statements, choose the most appropriate answer from the options given below :

1. A \((\mathrm{A})\) is not correct but \((\mathrm{R})\) is correct
2. B Both \((\mathrm{A})\) and \((\mathrm{R})\) are correct and \((\mathrm{R})\) is the correct explanation of (A)
3. C \((A)\) is correct but \((\mathrm{R})\) is not correct
4. D Both (A) and (R) are correct but (R) is not the correct explanation of (A)