Which blood vessel leaves the heart and supplies blood to all parts of the body?

The aorta is the correct choice because it is the main artery that originates from the left ventricle of the heart. Its function is to distribute oxygen-rich blood to the entire body through a network of branching arteries. Once blood is pumped out of the heart into the aorta, it travels through various systemic arteries that reach all organs and tissues, ensuring they receive the necessary oxygen and nutrients.

The pulmonary veins, while essential in transporting oxygenated blood from the lungs to the heart, do not supply blood to the rest of the body; instead, they return blood to the heart for circulation. The superior vena cava is responsible for bringing deoxygenated blood from the upper body back to the heart, whereas the coronary arteries supply blood specifically to the heart muscle itself, rather than the body as a whole. Thus, the aorta's unique role in distributing blood throughout the entire body clarifies why it is the correct answer.