【单选题】

A big difference between Kojo and Sorie was that ______.
A．Kojo took chemicals for some useful experiment but Sorie only wasted his in making an alcoholic drink.

B．Sorie was rich but Kojo was poor
C．Kojo had a guilty conscience but Sorie did not
D．when Kojo objected, Sorie proved that what they were doing was reasonable