Answer :
The following is missing for the question to be complete:
A. The Moon had craters
B. Sunspots
C. The moons of Jupiter
D. Venus' phases
E. The moons of Saturn
Answer: E. The moons of Saturn
Explanation: Galileo Galileo was a famous Italian astronomer known for his heliocentric model, which was the opposite of the Church's hard-line attitude and teachings, by which it was geocentric. Galileo is considered the initiator of modern astronomy because he observed the moon, the phases of Venus, the moons of Jupiter, the sunspots, and then the milky way. Then, he improved and upgraded the version of the telescope at the time, becoming the first to observe celestial bodies using a telescope. With the advancing telescope, he began with his discoveries, one of them being that the moon did not have a flat surface as previously believed, but that it had mountains, valleys, or features of Earth relief. What Galileo did not do, i.e what he did not observe, are the moons of Saturn.