**Core Concept**
Atrial fibrillation (AF) is a type of supraventricular tachycardia characterized by rapid and irregular atrial electrical activity, leading to a quivering or fibrillatory pattern in the atria. This condition can result from various underlying cardiac, non-cardiac, and electrolyte imbalances.

**Why the Correct Answer is Right**
Atrial fibrillation is often associated with conditions that lead to cardiac remodeling, structural heart disease, or increased sympathetic tone. Conditions like hypertension, coronary artery disease, heart failure, and thyroid disorders are known to contribute to the development of AF. The underlying mechanism involves the disruption of normal atrial electrical conduction, leading to the formation of reentrant circuits and fibrillatory waves.

**Why Each Wrong Option is Incorrect**
**Option A:** Mitral valve prolapse is a condition where the mitral valve leaflets bulge back into the left atrium during systole, which can lead to atrial enlargement and stretch, increasing the risk of developing AF.
**Option B:** Pulmonary embolism can cause a sudden increase in right heart pressure, leading to right atrial enlargement and increased risk of AF.
**Option C:** Hypokalemia is a condition of low potassium levels, which can disrupt the normal electrical conduction in the heart, making it a potential risk factor for AF.

**Clinical Pearl / High-Yield Fact**
Atrial fibrillation is a significant risk factor for stroke, and patients with AF should be on long-term anticoagulation therapy, unless contraindicated.

**Correct Answer:** D