Read the passage carefully and choose the best option (A, B, C or D).

Galileo Galilei was one of the first modern scientists. He was born in Pisa, Italy, in 1564. At first, he studied philosophy, but later he studied mathematics and astronomy. He was interested in the way the earth and other planets move around the sun. He found out several important facts about our world. He also started a new way of working in science. Before Galileo, scientists didn’t do experiments. They just guessed about how something happened. Galileo was different. He did not just make guesses. He did experiments and watched to see what happened.

 Galileo was famous for his study of how things fall. He was the first person to do experiments about this problem. Before, people thought that heavy things fell faster than light things. He found out that this was not true. He took a heavy ball and a light ball and he dropped them both from a high place. They fell at the same speed. This meant that weight is not important. This is the law of falling bodies. It is an important law for understanding our world.

The life of the scientist was not always easy in the 1500s. For example, Galileo got into trouble because of his scientific ideas. His ideas were not the same as the religious ideas at the same time. Many religious people did not agree with him. During his whole life he had to worry about this. He even went to prison for a while. But no one could stop him from thinking. He continued to look for scientific answers to his questions about the world.

Galileo studied all the following EXCEPT _______.