Final answer:
The heart (option A) is the organ that pumps blood throughout the body, utilizing various circulatory pathways to ensure oxygenated blood reaches all tissues and deoxygenated blood is returned for reoxygenation.
Step-by-step explanation:
The organ responsible for pumping blood throughout the human body is the heart. It is a complex muscle that performs this vital function by utilizing three divisions of the circulatory system: the coronary, pulmonary, and systemic circuits. The heart's structure, including its four inner chambers - the right and left atrium, and the right and left ventricles - allows it to effectively pump oxygen-rich blood through the arteries to the body and return oxygen-poor blood through the veins back to itself. Deoxygenated blood is sent to the lungs via the right ventricle, where it receives oxygen before being pumped out to the body. This efficacious process keeps every part of the body well-supplied with the necessary nutrients and oxygen.