Please choose the correct answer to the question: Denise was driving east over a hill in the afternoon, shortly after a rain shower. Suddenly the sun broke through the clouds, and she saw a rainbow ahead of her. Which of the following made the rainbow possible?

Answer1: Sunlight can be separated into all the colors of the rainbow. Answer2: Water reflects sunlight like a mirror to make it look colored. Answer3: Overhead black clouds reflect in puddles to cause a mirage. Answer4: Air pollution causes the sky to look colored under these conditions.

Answer format: answer1/answer2/answer3/answer4
Answer: answer1