Arrhenius model considers a base a compound that produces OH(-)
H2SO4 produces H(+) and is an acid
C6H12O6 is an organic product, sugar, that does not produce OH(-)
HOClO2 = HClO3, which produces H(+) and is an acid
NH3 is believed to ionize in water and produce NH4(+) and OH(-).
As per this the answer is NH3.
Nevertheless, NH3 is not a good example of bases as per Arrhenius model, because it is not so evident that NH3 produces OH(-).