**Core Concept**
Ketone bodies are water-soluble compounds produced by the liver as an alternative energy source when glucose is in short supply. They are formed through the breakdown of fatty acids in the liver.

**Why the Correct Answer is Right**
Ketone bodies are synthesized from acetyl-CoA in a process called ketogenesis. When blood glucose levels are low, the liver increases the production of acetyl-CoA from fatty acids, which are then converted into ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) through a series of enzyme-catalyzed reactions. This process occurs in the mitochondria of liver cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This is a distractor, as ketone bodies are not primarily formed in the kidneys. While the kidneys do play a role in metabolizing ketone bodies, they are not the primary site of their formation.
**Option B:** This is incorrect because ketone bodies are not formed from glycolysis. Glycolysis is the breakdown of glucose to pyruvate, which is then converted into acetyl-CoA and fed into the citric acid cycle. Ketone bodies are formed from acetyl-CoA, which is produced from fatty acid breakdown.
**Option C:** This is incorrect because ketone bodies are not primarily formed in the brain. While the brain can use ketone bodies as an energy source, they are not produced within the brain. Instead, they are transported to the brain from the liver via the bloodstream.

**Clinical Pearl / High-Yield Fact**
In diabetic ketoacidosis (DKA), the liver produces excessive amounts of ketone bodies due to the lack of insulin, leading to metabolic acidosis and potentially life-threatening complications.

**Correct Answer: C. Liver**