**Core Concept**
The acid-base status of a patient can be assessed using the arterial blood gas (ABG) values, pH, HCO3- (bicarbonate), and PCO2 (partial pressure of carbon dioxide). The ABC value or the Henderson-Hasselbalch equation is used to calculate the bicarbonate concentration that would be present if the blood were in a state of perfect acid-base balance.

**Why the Correct Answer is Right**
The Henderson-Hasselbalch equation is given by: pH = pKa + log10 ([HCO3-]/[H2CO3]), where [HCO3-] is the bicarbonate concentration and [H2CO3] is the concentration of carbonic acid. However, the equation can also be rearranged to solve for [HCO3-], which gives us: [HCO3-] = 24 * (PCO2/0.03) * 10^(pH-6.1). Given a pH of 7.2, PCO2 of 60 mmHg, and a pKa of 6.1 for carbonic acid, we can plug these values into the equation to get the expected bicarbonate concentration.

**Why Each Wrong Option is Incorrect**
**Option A:** There is no calculation provided to justify this answer.
**Option B:** There is no calculation provided to justify this answer.
**Option C:** There is no calculation provided to justify this answer.
**Option D:** There is no calculation provided to justify this answer.

**Clinical Pearl / High-Yield Fact**
When interpreting ABG values, it's essential to consider the patient's clinical context and the underlying cause of their acid-base disorder. In this case, a high PCO2 and high bicarbonate concentration suggest a respiratory acidosis with a compensatory metabolic alkalosis.

**Correct Answer:** D. **24**