In cis-1,3-dimethylcyclohexane, the diaxial chair has one CH3/CH3 1,3-diaxial interaction (15.4 kJ/mol) and two CH3/H 1,3-diaxial interactions (3.8 kJ/mol each); the diequatorial chair is free of such strain. The diaxial chair lies above the diequatorial chair by

1. A$15.4\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
2. B$15.2\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
3. C$30.6\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
4. D$23.0\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$