**Core Concept:** Distal convoluted tubule (DCT) is a crucial part of the nephron where various electrolyte reabsorption occurs. This process helps regulate electrolyte balance in the body.

**Why the Correct Answer is Right:** In the DCT, important electrolytes such as sodium (Na+) and chloride (Cl-) are reabsorbed. However, potassium (K+) is primarily reabsorbed in the collecting duct, not the DCT.

**Why Each Wrong Option is Incorrect:**

A. Calcium (Ca2+) reabsorption primarily occurs in the thick ascending limb (TAL) of the loop of Henle, not the DCT.
B. Magnesium (Mg2+) reabsorption also occurs in the TAL, not the DCT.
C. Sodium chloride (NaCl) reabsorption is a general term for the reabsorption of Na+ and Cl-, but the individual electrolytes Na+ and Cl- are absorbed in the DCT, not NaCl.
D. Potassium reabsorption, as explained above, occurs in the collecting duct, not the DCT.

**Clinical Pearl / High-Yield Fact:** Understanding the specific locations of electrolyte reabsorption in the nephron helps us differentiate between the roles of different nephron segments in maintaining electrolyte balance and acid-base homeostasis.

**Correct Answer:** D. Potassium reabsorption occurs in the collecting duct, not the DCT.