**Core Concept**
The question is about identifying the primary ketone body produced in the liver during fasting or carbohydrate deprivation. Ketone bodies are water-soluble molecules produced by the liver as a byproduct of fatty acid breakdown.

**Why the Correct Answer is Right**
Ketone bodies are synthesized in the liver through a process called beta-oxidation, where acetyl-CoA is converted into acetoacetate. Acetoacetate is then reduced to beta-hydroxybutyrate (BHB) or spontaneously decarboxylated to form acetone. Among these, BHB is the primary ketone body produced and utilized by the brain and other tissues as an alternative energy source. BHB is transported to peripheral tissues where it can be converted back to acetoacetate and then to acetyl-CoA for energy production.

**Why Each Wrong Option is Incorrect**
**Option A:** Acetone is a minor ketone body produced through spontaneous decarboxylation of acetoacetate, but it's not the primary ketone body.
**Option B:** Acetoacetate is an intermediate in the synthesis of ketone bodies, but it's not the primary ketone body utilized by tissues.
**Option C:** This option is blank and cannot be evaluated. However, if a distractor were provided, it would be evaluated similarly to the other options.

**Clinical Pearl / High-Yield Fact**
Ketone bodies serve as an important energy source during fasting, starvation, or prolonged exercise. However, excessive ketone production can lead to ketoacidosis, a potentially life-threatening condition.

**Correct Answer: B. Beta-hydroxybutyrate**