15. Which of the following statements relating to molecular orbital (MO) theory is incorrect? (A) Combination of two atomic orbitals produces one bonding and one antibonding MO. (B) A bonding MO is lower in energy than the two atomic orbitals from which it is formed. (C) Combination of two 2p orbitals may result in either σ or π MOs. (D) A species with a bond order of zero will not be stable. (E) In a stable molecule having an even number of electrons, all electrons must be paired.