Concept:A satellite is any natural or artificial body that orbits a planet. The Earth has one natural satellite.Explanation:The Sun is a star at the centre of the solar system, so it is not a satellite of the Earth.Mars and Saturn are planets that revolve around the Sun, not around the Earth.The Moon is a natural rocky body that orbits the Earth in a fixed path.Because the Moon revolves around the Earth, it is correctly described as the Earth's satellite.Answer:The correct answer is B. the moon.