**Core Concept**
Bartter's syndrome is a rare genetic disorder characterized by defective function of the ion transport mechanisms in the thick ascending limb of the loop of Henle in the kidneys. This leads to impaired reabsorption of sodium, potassium, and chloride ions, resulting in hypokalemia, metabolic alkalosis, and normal to low blood pressure.

**Why the Correct Answer is Right**
The correct answer should describe a characteristic feature of Bartter's syndrome. Bartter's syndrome is caused by mutations in genes encoding for the Na-K-2Cl cotransporter (NKCC2), the Cl-K2Cl cotransporter (CLCNKB), or the Barttin protein (BSND). These mutations disrupt the normal ion transport mechanisms in the thick ascending limb of the loop of Henle, leading to excessive urinary loss of sodium, potassium, and chloride ions. The resulting hypokalemia and metabolic alkalosis are hallmarks of the disorder.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect - Bartter's syndrome is indeed characterized by hypokalemia, which is a result of excessive potassium loss in the urine.
**Option B:** Incorrect - Metabolic alkalosis is a common feature of Bartter's syndrome due to the impaired reabsorption of chloride ions in the thick ascending limb of the loop of Henle.
**Option C:** Incorrect - Normal to low blood pressure is a characteristic feature of Bartter's syndrome due to the impaired reabsorption of sodium ions.
**Option D:** Incorrect - This statement should be the correct answer as Bartter's syndrome is not associated with hyperkalemia.