**Core Concept**
Hypokalemia is a condition characterized by low potassium levels in the blood, which can lead to various cardiac, muscular, and renal complications. The underlying mechanism involves the imbalance between potassium intake, excretion, and shift between cells and the extracellular fluid.

**Why the Correct Answer is Right**
Hypokalemia is associated with a range of clinical manifestations, including muscle weakness, fatigue, and cardiac arrhythmias. The pathophysiology involves the inhibition of the sodium-potassium pump, leading to an increase in intracellular potassium and a decrease in the electrochemical gradient across cell membranes. This can cause hyperpolarization of the cardiac muscle cells, leading to a prolongation of the QT interval and an increased risk of arrhythmias.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hypokalemia is not typically associated with hypernatremia.
**Option B:** This option is incorrect because hypokalemia is not directly related to the renin-angiotensin-aldosterone system (RAAS).
**Option C:** This option is incorrect because hypokalemia is not a common complication of diabetes mellitus.

**Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that hypokalemia can cause a prolongation of the QT interval, which increases the risk of cardiac arrhythmias, including torsades de pointes.

**Correct Answer:** C. Muscle weakness