Which of the following are ketone bodies

The correct option is "All of the above".

Ketone bodies are three water-soluble molecules containing the ketone group, or structurally related to them, that are produced by the liver from fatty acids during periods of low food intake (fasting), carbohydrate-restrictive diets, starvation, prolonged intense exercise, or in pathological states like untreated type 1 diabetes mellitus.

The three substances classified as ketone bodies are:
1. Acetoacetate: This is the primary ketone body produced in the mitochondrial matrix of hepatocytes.
2. ꞵ-hydroxybutyrate: Although technically a carboxylic acid rather than a ketone (since its carbonyl group is reduced to a hydroxyl group), it is synthesized from acetoacetate and is metabolically classified as a ketone body.
3. Acetone: Produced via the spontaneous non-enzymatic decarboxylation of acetoacetate. It is the least abundant ketone body and is excreted through the breath, giving it a characteristic fruity odor.

Since acetoacetate, acetone, and ꞵ-hydroxybutyrate are all classified as ketone bodies, the correct choice is indeed "All of the above".