True of the following
**Explanation**
**Core Concept**
The question pertains to the pathophysiology of a specific condition, involving the regulation of electrolyte balance and acid-base homeostasis in the human body.
**Why the Correct Answer is Right**
The correct answer is related to the concept of bicarbonate reabsorption in the proximal convoluted tubule of the nephron. Bicarbonate ions (HCO3-) are reabsorbed in exchange for chloride ions (Cl-) in the presence of carbonic anhydrase, an enzyme that facilitates the conversion of carbon dioxide and water to carbonic acid, which then dissociates into bicarbonate and protons. This process is crucial for maintaining acid-base balance and preventing metabolic acidosis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it refers to a different electrolyte transport mechanism in the nephron, which is not directly related to the regulation of acid-base balance.
**Option B:** This option is incorrect because it involves a different organ system, whereas the correct answer pertains to renal physiology.
**Option C:** This option is incorrect because it refers to a different aspect of electrolyte balance, which is not directly related to bicarbonate reabsorption.
**Clinical Pearl / High-Yield Fact**
The kidneys play a critical role in maintaining acid-base balance through the regulation of bicarbonate reabsorption and hydrogen ion excretion. A deficiency in carbonic anhydrase can lead to impaired bicarbonate reabsorption and metabolic acidosis.
**Correct Answer: A. Bicarbonate ions are reabsorbed in exchange for chloride ions in the presence of carbonic anhydrase in the proximal convoluted tubule.**