**Core Concept**
Chronic Renal Failure (CRF) is characterized by a gradual loss of renal function, leading to inadequate excretion of waste products and electrolytes. This impairment affects the body's acid-base balance, resulting in metabolic disturbances.

**Why the Correct Answer is Right**
In CRF, the kidneys fail to properly excrete hydrogen ions and reabsorb bicarbonate ions, leading to an accumulation of acidic substances in the blood. This results in a decrease in bicarbonate levels and an increase in hydrogen ion concentration, causing metabolic acidosis. The kidneys' inability to produce erythropoietin also contributes to the development of anemia, which further exacerbates the metabolic disturbances. The decreased renal function also impairs the kidneys' ability to regulate potassium levels, leading to hyperkalemia, which can further contribute to the development of metabolic acidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Respiratory acidosis is characterized by an increase in carbon dioxide levels in the blood, which is not directly related to the pathophysiology of CRF.
**Option B:** Respiratory alkalosis is caused by a decrease in carbon dioxide levels in the blood, which is not associated with CRF.
**Option D:** Metabolic alkalosis is characterized by an increase in bicarbonate levels in the blood, which is the opposite of what occurs in CRF.

**Clinical Pearl / High-Yield Fact**
In patients with CRF, it is essential to monitor electrolyte levels, including potassium, sodium, and bicarbonate, as well as acid-base balance, to prevent complications related to metabolic acidosis.

**✓ Correct Answer: C. Metabolic acidosis**