(A) : Half-life period of a reaction of first order is independent of initial concentration.
(R) : Half-life period for a first order reaction is equal to $\frac{2.303}{ \mathrm{K}}\log 2$

Both (A) and (R) are correct and (R) is the correct explanation of (A).

Both (A) and (R) are correct but (R) is not the correct explanation of (A).

(A) is correct but (R) is wrong.

(A) and (R) both are wrong.