Which of the following describes ventricular fibrillation?

Ventricular fibrillation is characterized by disorganized electrical activity within the ventricles, which leads to ineffective heart contractions. In this condition, the electrical signals in the ventricles fire in a chaotic manner rather than resulting in coordinated heartbeats. As a result, the heart cannot effectively pump blood, leading to a loss of pulse and severely diminished blood flow to vital organs, which can be life-threatening if not promptly treated.

The other options describe different cardiac rhythm characteristics. Regular rhythms, whether rapid or slow, indicate a coordinated electrical impulse leading to effective contractions. A normal heart rhythm suggests a proper functioning of the heart's conduction system. In contrast, the chaotic nature of ventricular fibrillation does not allow for such organized electrical activity or effective contractions, underscoring why option B accurately captures the essence of ventricular fibrillation.