Concept:The high solubility of ethanol in water is due to intermolecular hydrogen bonding between ethanol and water molecules.Explanation:Ethanol contains a hydroxyl group, −OH.Water, H2O, also contains −OH groups.The −OH group of ethanol forms hydrogen bonds with water molecules.This strong attraction allows ethanol to dissolve easily in water.The solubility is not caused by its boiling point, freezing point, or merely its covalent nature.Answer:D. hydrogen bonding