Answer: B - At 4 minutes without oxygen, brain cell death begins.
Though each case is different, anoxic brain damage can occur within a few minutes after the brain is deprived of oxygen. In the case of a CPR patient with no pulse, the timeline for anoxic brain damage would depend on how long the brain has gone without oxygen. The longer the brain is deprived of oxygen, the greater the risk of anoxic brain damage. However, it is important to note that every case is different and that the timeline for anoxic brain damage can vary depending on a number of factors, including the individual's age, overall health, and the underlying cause of cardiac arrest.
