The correct option is B MnO+3
Mn2O7 arises as a dark green oil by the addition of concentrated H2SO4toKMnO4. The reaction initially produces permanganic acid, HMnO4 (structurally, HOMnO3), which is dehydrated by sulfuric acid to form its anhydride, Mn2O7.
2KMnO4+(cold)2H2SO4Mn2O7+H2O+2KHSO4
Mn2O7 can react further with sulfuric acid to give the remarkable cation MnO+3.