Given a scientific passage and an answer, generate a question for the given answer.

Example Input: Passage: Sperm are produced in the testes in the process of spermatogenesis. Answer: spermatogensis
Example Output: What process creates sperm?

Example Input: Passage: Hinge Joint. The knee joint is a hinge joint. Like a door hinge, a hinge joint allows backward and forward movement. Answer: hinge joint
Example Output: What type of joint is the knee joint?

Example Input: Passage: Our solar system has only one star. But many stars are in systems of two or more stars. Two stars that orbit each other are called a binary star system . If more than two stars orbit each other, it is called a multiple star system. Figure below shows two binary star systems orbiting each other. This creates an unusual quadruple star system. Answer: one
Example Output:
How many stars are in our solar system?