Which body system is NOT listed among the systems of the body?

The body systems include various physiological and functional networks that contribute to overall health. The nervous system is responsible for transmitting signals between different parts of the body; the digestive system breaks down food for nutrient absorption; and the endocrine system regulates body functions through hormones.

The solar system, however, does not pertain to human anatomy or physiology. Instead, it refers to the collection of celestial bodies - including the sun, planets, and moons - that exists outside of Earth. Since the question asks for a body system and the solar system is not a part of human biology, it is rightly noted as the option that does not belong among recognized body systems.