**Core Concept**
Metabolic acidosis is a condition characterized by an excessive accumulation of acid in the blood, leading to a decrease in blood pH. This can result from various conditions, including increased acid production, decreased acid excretion, or increased loss of bicarbonate.

**Why the Correct Answer is Right**
Metabolic acidosis can be caused by several conditions, including diabetic ketoacidosis, lactic acidosis, and renal tubular acidosis. Diabetic ketoacidosis occurs when the body produces high levels of ketones due to a lack of insulin, leading to an accumulation of acidic substances in the blood. Lactic acidosis is caused by an excessive production of lactic acid, often due to tissue hypoxia or impaired lactate metabolism. Renal tubular acidosis is a condition characterized by a defect in the kidneys' ability to reabsorb bicarbonate, leading to an excessive loss of bicarbonate and metabolic acidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Diabetic ketoacidosis is a well-known cause of metabolic acidosis, so this option is incorrect.
**Option B:** Lactic acidosis is another common cause of metabolic acidosis, making this option incorrect.
**Option C:** Renal tubular acidosis can also cause metabolic acidosis, so this option is incorrect.

**Clinical Pearl / High-Yield Fact**
Metabolic acidosis can be a life-threatening condition, requiring prompt recognition and treatment to prevent complications such as cardiac arrest and multi-organ failure. It's essential for healthcare professionals to be aware of the various causes and manifestations of metabolic acidosis to provide timely and effective care.

**Correct Answer: D. Chronic kidney disease.**