The correct option is A (a) and (b) only
Disproportionation reactions are those in which the same reactant species is oxidised and reduced, this happens in a) and b) since the oxidation number of:
Copper changes from +1 to +2 and 0 in a)
Manganese changes from +6 to +7 and +4 in b)
In c), Mn goes from + 7 to +6 and +4, this is reduction only.
In d), Mn has two oxidation states - +7 and +2 which become +4. This is the reverse of disproportionation.