What compensatory mechanism involved in both chronic heart failure and decompensated heart failure leads to fluid retention and edema?

A. Ventricular fibrillation is a life-threatening arrhythmia, not a compensatory mechanism for heart failure. B. Increased intracranial pressure (ICP) is unrelated to heart failure compensation. C. The renin-angiotensin-aldosterone system (RAAS) is activated in heart failure to maintain blood pressure and perfusion. This leads to sodium and water retention, causing fluid buildup and edema. D. Atrial flutter is a cardiac arrhythmia, not a compensatory mechanism causing fluid retention.