The correct answer is C. The heart pumps blood to the blood vessels, and the vessels transport the blood throughout the human body.
Step-by-step explanation:
A system is a set of interconnected elements that work to develop a specific function and create a whole or a unit. This means in a system each part has one function but this contributes to all the system.
According to this, the one that is an example of the parts of a system working together is "The heart pumps blood to the blood vessels, and the vessels transport the blood throughout the human body", because in this case the heart, blood vessels, veins, etc are part of a unit or system called the circulatory system that pumps blood to all the body. Additionally, each section or organ in this system has a function as the heart pumps the blood and vessels are the ones that take the blood to all parts of the body.