Which one of the following is a redox reaction?
◦ 2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g)
◦ 2KBr(aq) + Pb(NO3)2(aq) → 2KNO3(aq) + PbBr2(s)
◦ CaBr2(aq) + H2SO4(aq) → CaSO4(s) + 2HBr(g)
◦ H+(aq) + OH– (aq) → H2O(l)
◦ CO32– (aq) + HSO4–(aq) → HCO3– (aq) + SO42– (aq)