Answer: D. He theorized that the Earth was the center of the universe.
Explanation: Ptolemy was an ancient Greek astronomer and a mathematician who believed that the earth was the center of the universe which led to the geocentric theory--coined from the greek word 'geo' which means earth. Albeit incorrect, this flawed view of the universe was acceptable for centuries until it was discredited. However, it is remarkable how using mathematics (especially geometry) and by tracking the stars he was able to track and predict the movement of the planets.
