Which of the following reactions are disproportionation reactions ? (i) `Cu^(+) rarr Cu^(2+)+ Cu` (ii) `3MnO_4^(2-)+ 4H^(+) rarr 2MnO_4^(-)+ MnO_2 + 2H_2O` (iii) `2KMnO_4 rarr K_2MnO_4 +MnO_2 + O_2 ` (iv) `2MnO_4^(-)+ 3Mn^(2+)+ 2H_2O rarr 5MnO_2 +4H^(+)`

Options

A. i ,ii
B. i,ii, iii
C. ii, iii, iv
D. i, iv