**Core Concept**
The patient's blood gas measurements indicate a respiratory acidosis, characterized by a low pH, elevated pCO2, and normal pO2. This condition occurs when there is an imbalance in the respiratory system, leading to inadequate ventilation and retention of carbon dioxide.

**Why the Correct Answer is Right**
The elevated pCO2 level is a key indicator of respiratory acidosis, as the body's ability to expel CO2 is impaired. This can be due to various factors, such as respiratory depression, lung disease, or neuromuscular disorders. The normal pO2 level suggests that the issue is primarily with CO2 elimination rather than oxygenation. The low pH level confirms the presence of acidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a normal anion gap metabolic acidosis would typically present with a low pCO2 level, not an elevated one.

**Option B:** This option is incorrect because a lactic acidosis would typically present with a high anion gap metabolic acidosis, which is not indicated by the blood gas values.

**Option C:** This option is incorrect because a diabetic ketoacidosis would typically present with a high anion gap metabolic acidosis, which is not indicated by the blood gas values.

**Clinical Pearl / High-Yield Fact**
In cases of respiratory acidosis, it is essential to assess the patient's respiratory status, including their respiratory rate, tidal volume, and lung function, to identify the underlying cause and implement appropriate treatment.

**Correct Answer: C. Respiratory acidosis.**