Assertion `(A)`: Colour of `KMnO_4` disappears when dihydrogen gas is bubbled through it.
Reason `(R)` :Dihydrogen gas is highly inflammable.
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.