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

Ex Input:
Passage: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. Only with fluorine does oxygen form compounds in positive oxidation states. Answer: positive oxidation states

Ex Output:
Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. only with fluorine does oxygen form compounds in this?

Ex Input:
Passage: Infectious diseases are diseases that spread from person to person. They are caused by pathogens such as bacteria, viruses or fungi. What can you do to avoid infectious diseases? Eating right and getting plenty of sleep are a good start. These habits will help keep your immune system healthy. With a healthy immune system, you will be able to fight off many pathogens. The next best way is to avoid pathogens. Though this is difficult, there are steps you can take to limit your exposure to pathogens. Answer: immune system

Ex Output:
What system is responsible for defending your body against sickness?

Ex Input:
Passage: Clouds block sunlight in the day. Clouds trap heat in the atmosphere at night. Answer: heat

Ex Output:
What do clouds trap into the atmosphere at night?