Assertion: `MnO` is basic whereas `Mn_2O_7` is acidic.
Reason: Higher the oxidation state of a transition metal in its oxide, greater is the acidic character.
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.