Final answer:
The compound with the highest viscosity out of the given options is ethylene glycol (HOCH₂CH₂CH₂CH₂OH) due to stronger intermolecular forces.
Step-by-step explanation:
In this question, we need to determine the substance with the highest viscosity. Viscosity is the measure of a fluid's resistance to flow. The higher the viscosity, the thicker the fluid. To compare the viscosities of the substances given, we need to consider their chemical structures and intermolecular forces.
Out of the three options, the compound with the highest viscosity is c. HOCH₂CH₂CH₂CH₂OH (ethylene glycol). Ethylene glycol has more hydroxyl groups (-OH), which results in stronger hydrogen bonding between molecules. The intermolecular forces in ethylene glycol are stronger compared to the other options, causing it to have higher viscosity.