**Core Concept**
Halothane is a volatile anesthetic agent that undergoes hepatic metabolism, producing several metabolites, including trifluoroacetic acid and trichloroethylene. The extent of halothane metabolism is a critical factor in determining its pharmacokinetics and potential toxicity.

**Why the Correct Answer is Right**
Approximately 20-30% of halothane is metabolized by the liver, primarily through the action of cytochrome P450 enzymes. This metabolic pathway leads to the formation of reactive intermediates, which can contribute to halothane-induced hepatotoxicity. The metabolism of halothane is also influenced by factors such as the presence of other anesthetic agents and the patient's liver function.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately reflect the percentage of halothane that is metabolized.
* **Option B:** This option is incorrect because it is higher than the actual percentage of halothane that is metabolized.
* **Option D:** This option is incorrect because it is lower than the actual percentage of halothane that is metabolized.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the metabolism of halothane can be affected by other factors, such as the presence of other anesthetic agents and the patient's liver function. This knowledge is crucial in managing patients who are undergoing halothane anesthesia, particularly those with pre-existing liver disease.

**Correct Answer: C. 20-30%**