Given below are the two statements: one is labeled as Assertion \((A)\) and the other is labeled as Reason \((R)\). Assertion \((A)\): There is a considerable increase in covalent radius from \(\mathrm{N}\) to \(\mathrm{P}\). However from \(As\) to \(Bi\) only a small increase in covalent radius is observed. Reason \((R)\): covalent and ionic radii in a particular oxidation state increases down the group. In the light of the above statement, choose the most appropriate answer from the options given below:

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