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

Ex Input:
Passage: The atmosphere is a crucial part of the water cycle. It is an important reservoir for water, and the source of precipitation. Answer: the atmosphere

Ex Output:
What is the source of precipitation?

Ex Input:
Passage: Potential energy is energy that is stored in a person or object. Answer: potential energy

Ex Output:
Energy that is stored in a person or object is called?

Ex Input:
Passage: White blood cells called phagocytes travel to areas of the body that are inflamed. Answer: phagocytes

Ex Output:
White blood cells called what travel to areas of the body that are inflamed?