Which of the following symptoms is commonly associated with sudden cardiac arrest?

Sudden loss of consciousness is commonly associated with sudden cardiac arrest because during a cardiac arrest, the heart stops pumping blood effectively. This immediate cessation of blood flow to the brain results in a rapid loss of consciousness, typically within seconds.

The other symptoms listed may occur in various medical conditions but are not as definitive for cardiac arrest. For instance, sweating and nausea may be present in heart attack scenarios or other medical issues, while difficulty breathing can be related to numerous respiratory or cardiac problems. Severe headaches might indicate different conditions but are not specifically linked to sudden cardiac arrest. Therefore, the hallmark of sudden cardiac arrest that is most recognizable is the sudden loss of consciousness, highlighting the urgency of immediate medical intervention.