For most compounds with a single keto group in the molecule, equilibrium favors the keto form over the enol form of the compound. this is due largely to what?

Single Keto group favors keto group over enol group due to following reason.

Unlike in beta-dicarbonyl compounds (which favors enol form) single keto group ketones are more stable in keto form.

For stability I searched for the bond energies. Below are the two forms. You can easily see the three different types of bonds and their energies. The main difference comes in the bond energy of C=O (carbonyl) group, which has the highest energy. Other energies are some what close to each other. 

Remember: Greater the bond energies, greater will be the stability of compound.

Result:
          The reason is "C=O bond is much stronger than C=C Bond".

No multiple choices?