18. Photodissociation of chlorine molecules (Cl2 + light 2 Cl‧) creates highly reactive chlorine radicals, which play important roles in chlorination of hydrocarbons, polymerization, and catalyzing the ozone decomposition reaction. According to the molecular orbital theory, what is the lowest-energy excitation pathway (initial MO → final MO) that causes a ground-state Cl2 molecule to dissociate? (Assuming the MO's have higher energy than the MO.) (A) (B)(C) (D) (Ε)