(A) In `S_(N^(2))` reactions, complete inversion of configuration takes place.
(R) In `S_(N^(1))` reactions, retention but not the inversion takes place,
A. If both (A) and (R) are correct and (R) is the correct explanation of (A).
B. If both (A) and (R) are correct but (R) is not the correct explanation of (A).
C. If (A) is correct but (R) is incorrect.
D. IF (A) is incorrect but (R) is correct.