Final answer:
The compound with the highest boiling point is NaCl.
Step-by-step explanation:
Electrostatic interactions are strongest for an ionic compound, so we expect NaCl to have the highest boiling point. To predict the relative boiling points of the other compounds, we must consider their polarity (for dipole-dipole interactions), their ability to form hydrogen bonds, and their molar mass (for London dispersion forces).
C₆H₁₂O₆ is a polar compound that can form hydrogen bonds, but it has a lower molar mass than NaCl. O₂ is a nonpolar compound with London dispersion forces, but it has a lower molar mass than NaCl. H₂O is a polar compound that can form hydrogen bonds, but it has a lower molar mass than NaCl.
Therefore, the correct answer is NaCl.