Please choose the correct answer to the question: Ptolemy was an ancient astronomer who thought Earth was the center of the universe. When he made observations that were inconsistent with this, he proposed a phenomenon called "epicycles" to explain the observations. How was Ptolemy's process similar to the modern scientific process?

Answer1: Ptolemy based his model partly on a belief system. Answer2: Observations inspired Ptolemy to modify his explanations. Answer3: Ptolemy tried to describe the universe instead of explaining it. Answer4: Experiments were the basis of Ptolemy's model of the universe.

Answer format: answer1/answer2/answer3/answer4