Which of the following rhythms is shockable?

Ventricular Fibrillation (VF) is a shockable rhythm because it represents a chaotic electrical activity in the heart that leads to ineffective pumping of blood. The primary goal in the case of VF during a cardiac arrest is to restore a normal rhythm and effective circulation. Applying an electric shock to the chest via a defibrillator can disrupt this disordered electrical activity and potentially allow the heart to regain a normal sinus rhythm.

Shockable rhythms are characterized by the presence of organized electrical activity that is amenable to defibrillation. VF falls into this category, as the purpose of defibrillation is to restore coordinated electrical activity to the heart.

In contrast, rhythms such as asystole are non-shockable because they indicate a complete lack of electrical activity in the heart. Normal sinus rhythm, while a healthy heartbeat, does not require defibrillation and is not a situation of cardiac arrest. Similarly, sinus bradycardia, which is a slower heart rate, is typically not treated with defibrillation unless it is symptomatic and accompanied by other critical conditions. Thus, VF is clearly the only rhythm listed that qualifies as shockable due to its clinical significance in life-threatening arrhythmias.