The main organ of the circulatory system is the heart. The heart is a fist-sized muscle a little to the left of the center of the chest. Every day, it beats about 100,000 times, pumping about 2,000 gallons of blood. The heart has four chambers: the right atrium, right ventricle, left atrium and left ventricle. Each chamber is separated by a valve. These valves work like one-way doors that keep blood flowing in the right direction. The valves open to let blood flow through, then quickly close to prevent it from flowing backward.
Based on the passage, which of these is most likely true?
A
The heart beats once per hour.
B
The heart has eight separate chambers.
C
Blood circulates through the body in one direction.
D
The human body contains about 2,000 gallons of blood.
C
Blood circulates through the body in one direction.