Concept:Fats and oils are natural esters formed when the trihydric alcohol glycerol combines with fatty acids.
Explanation:A fat or oil molecule is produced by esterification between fatty organic acids and glycerol.
Glycerol is a trihydric alkanol because it contains three hydroxyl groups, with the formula
C3H5(OH)3.
This allows it to form three ester linkages with fatty acid molecules, producing a triglyceride.
Ethanol and methanol are monohydric alkanols because each contains only one hydroxyl group.
Glycol is a dihydric alkanol because it contains only two hydroxyl groups.
Only glycerol possesses the three hydroxyl groups described as trihydric.
Therefore, the alkanol combined with fatty acids in fats and oils is glycerol.
Answer:D. Glycerol