What does a stroke (CVA) occur from?

A stroke, or cerebrovascular accident (CVA), primarily occurs due to a disruption in the blood supply to a part of the brain. The blocking of blood vessels in the brain, often referred to as an ischemic stroke, can happen suddenly and sometimes without any prior illness. This blockage can be caused by various factors, such as a blood clot or an embolism, which interrupts the oxygen and nutrient supply critical for brain tissue survival.

The process leading to a stroke can indeed develop over time, but the acute event is characterized by the immediate blockage of blood flow. This understanding is essential for recognizing the urgency of medical intervention during a stroke, as timely treatment can mitigate brain damage and improve outcomes for the individual affected.

While loss of blood flow is related to age-related factors and gradual plaque buildup can contribute to stroke risk over time, the immediate cause of a stroke is the blockage itself. Therefore, option B identifies the critical, acute event that leads to the stroke.