**Core Concept**
The condition described is likely related to a disturbance in the body's normal acid-base balance, specifically a metabolic acidosis. This can occur due to an imbalance in the production or excretion of acids and bases within the body.

**Why the Correct Answer is Right**
The most probable cause of metabolic acidosis is the accumulation of acidic substances or the loss of bicarbonate ions (HCO3-). This can occur due to various reasons such as diabetic ketoacidosis, lactic acidosis, or renal failure. In diabetic ketoacidosis, the body's inability to produce enough insulin leads to an accumulation of ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone), which are acidic in nature. These ketone bodies can lead to a significant increase in the anion gap, causing metabolic acidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specifically address the underlying cause of metabolic acidosis.
**Option B:** This option is incorrect because it is not a direct cause of metabolic acidosis.
**Option C:** This option is incorrect because it is not a common cause of metabolic acidosis.

**Clinical Pearl / High-Yield Fact**
A key aspect to remember is that metabolic acidosis is often associated with an increased anion gap, which can be calculated as the difference between the sodium concentration and the sum of chloride and bicarbonate concentrations.

**Correct Answer: D. Diabetic ketoacidosis.**