Answer:
B. The planets vary in size and composition.
Step-by-step explanation:
Galileo was an Italian scientist and he was the first person to use a telescope in the field of astronomy. Although, the first telescope was invented by Sir Isaac Newton.
A telescope can be defined as an optical instrument or device which comprises of a curved mirror and lenses used for viewing distant objects i.e objects that are very far away such as stars and other planetary bodies.
One of the first astronomers to use a telescope was Galileo. Using his telescope he discovered that Jupiter had four moons and each night, the four moons, seen as points of light, appeared to change positions slightly. Therefore, this observation gave further evidence that the planets vary in size and composition. The slight change in the position of the moon indicate that planetary bodies have a variation in size and matter (constituent elements) that make them up.