**Core Concept**
The question tests the understanding of the physiological effects of acetazolamide, a **carbonic anhydrase inhibitor**, on acid-base balance in the body. Acetazolamide is used in the treatment of glaucoma to decrease intraocular pressure.

**Why the Correct Answer is Right**
Acetazolamide inhibits **carbonic anhydrase**, an enzyme that plays a crucial role in the reabsorption of bicarbonate ions in the proximal convoluted tubule of the kidneys. This inhibition leads to increased excretion of bicarbonate ions, resulting in **metabolic acidosis**. The patient's arterial pH of 7.34, which is slightly acidic, and a low plasma HCO3- of 15 mEq/L, are indicative of metabolic acidosis. The aerial PCO2 of 29mmHg suggests a compensatory decrease in CO2 levels, attempting to normalize the pH.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, assuming it's not the correct answer.
**Option B:** Not provided, assuming it's not the correct answer.
**Option C:** Not provided, assuming it's not the correct answer.
**Option D:** Not provided, assuming it's not the correct answer.

**Clinical Pearl / High-Yield Fact**
In patients treated with acetazolamide, monitoring for signs of metabolic acidosis is crucial. The development of metabolic acidosis is a known side effect of this medication, and understanding its mechanism is key to managing patients on this therapy.

**Correct Answer:** D. Metabolic acidosis