The correct option is D 50% H2SO4
H2O2 is prepared commercially by electrolysis of 50% H2SO4.
Here, the H2SO4 is electrolysed to H2S2O8 and then it is hydrolysed to get H2SO4 and H2O2
Reactions at Cathode:
2H++2e−→H2
Reaction at anode:
2HSO−4→H2S2O8+e−
Hydrolysis of H2S2O8:
H2S2O8+H2O→H2SO5+H2SO4
H2SO5+H2O→H2SO4+H2O2