Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The radius vector from the Sun to a planet sweeps out equal areas in equal intervals of time and thus areal velocity of planet is constant.
Reason (R) : For a central force field the angular momentum is a constant.
In the light of the above statements, choose the most appropriate answer from the options given below :

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