What is the only positive ion found in H2SO4(aq)?

a. ammonium ion
b. hydronium ion
c. hydroxide ion
d. sulfate ion

The answer's b, but I don't understand why.

2 answers

The ionization of H2SO4 in aq solution is
H2SO4 + H2O ==> H3O^+ + HSO4^-
for an arrhenius acid, the only positive ion can be H+, or OH-. Therefore, hydronium is the answer because it should be the only one that is positive, plus all the other answers can't be positive.