The correct answer is option 4, the heart. The heart is a vital organ that works continuously without resting. It is responsible for pumping oxygen-rich blood to all parts of the body. The heart beats around 100,000 times per day, pumping around 2,000 gallons of blood. It works tirelessly to ensure that all organs and tissues receive the oxygen and nutrients they need to function properly. This constant activity is what allows the heart to keep the body alive. While other organs, such as the eyes, pancreas, and liver, are also important in their own ways, they do not have the same level of continuous activity as the heart.