Assertion (A) : Dinegative anion of oxygen `(O^(2-))` is quite common but di-negative anion of sulphur `S^(2-)` is less common.
Reason (R) :Covalency of oxygen is two.
A. Both A and R true and R is the correct explanation of A
B. Both A and R true and R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true