**Core Concept**
Bicarbonate absorption is a critical process in the renal physiology, where the kidneys regulate acid-base balance by adjusting the amount of bicarbonate reabsorbed into the bloodstream. This process primarily occurs in the proximal convoluted tubule (PCT) of the nephron.

**Why the Correct Answer is Right**
In the PCT, bicarbonate absorption is facilitated by the sodium-bicarbonate cotransporter (NBCe1), which is an electrogenic cotransporter that reabsorbs sodium and bicarbonate ions in exchange for potassium ions. This process is essential for maintaining the acid-base balance and ensuring that the blood pH remains within a narrow range. The NBCe1 cotransporter is highly efficient, and up to 85% of filtered bicarbonate is reabsorbed in the PCT.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the proximal convoluted tubule (PCT) is the primary site of bicarbonate absorption, not the distal convoluted tubule.
* **Option B:** This option is incorrect because the loop of Henle is primarily involved in water and ion reabsorption, but not bicarbonate absorption.
* **Option C:** This option is incorrect because the collecting duct is primarily involved in potassium and hydrogen ion secretion, but not bicarbonate absorption.

**Clinical Pearl / High-Yield Fact**
The kidneys can regulate acid-base balance by adjusting bicarbonate reabsorption and hydrogen ion excretion. In conditions of metabolic acidosis, the kidneys can increase bicarbonate reabsorption to help correct the acid-base imbalance.

**Correct Answer: C. Collecting duct.