Which of the following is a known cause of cardiac arrest?

Drowning is recognized as a known cause of cardiac arrest because it can lead to a lack of oxygen in the bloodstream, resulting in hypoxia. When water enters the airway, the body is unable to take in oxygen, which can cause the heart to stop pumping effectively. This is particularly critical in situations where drowning occurs, as the person's ability to breathe and maintain adequate oxygen levels is severely compromised.

In contrast, high blood pressure is a risk factor for heart disease but does not directly cause cardiac arrest. Ignoring symptoms, while potentially detrimental, is not a direct cause. Regular exercise is generally associated with heart health and does not lead to cardiac arrest; in fact, it can help improve cardiovascular fitness and reduce the risk of heart-related issues. Thus, drowning stands out as a significant and direct cause of cardiac arrest due to the immediate effects it has on breathing and oxygenation.