**Core Concept**
The given laboratory values (pH = 7.2, HCO3- = 10 meq/L, PCO2 = 30 mm Hg) indicate a mixed acid-base disorder, specifically a combination of metabolic acidosis and respiratory acidosis.

**Why the Correct Answer is Right**
The patient has a low bicarbonate level (HCO3- = 10 meq/L), indicating a metabolic acidosis. However, the pH is not as low as expected, suggesting a compensatory increase in PCO2, which is elevated at 30 mm Hg. This increase in PCO2 is an attempt by the body to compensate for the metabolic acidosis by increasing CO2 production, which reacts with water to form carbonic acid, thereby increasing H+ ions and decreasing pH. However, in this case, the increase in PCO2 is not sufficient to fully compensate for the metabolic acidosis, resulting in a mixed acid-base disorder.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot evaluate it.
* **Option B:** This option is also not provided, so we cannot evaluate it.
* **Option C:** This option is also not provided, so we cannot evaluate it.
* **Option D:** This option is also not provided, so we cannot evaluate it.

**Clinical Pearl / High-Yield Fact**
When evaluating acid-base disorders, it's essential to consider the patient's underlying condition and the potential causes of the acid-base imbalance. In this case, the patient's mixed acid-base disorder may be caused by a combination of factors, such as chronic obstructive pulmonary disease (COPD) and diabetes mellitus.

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