Assertion `(A)`: Ferrocyanide ion oxidises `H_2O_2` to `H_2O`.
Reason `(R)` : Oxidation product of `H_2O_2` is `O_2.`
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.