TASK DEFINITION: Given a scientific passage and an answer, generate a question for the given answer.
PROBLEM: Passage: Mouth Brooding. Some species of fish carry their fertilized eggs in their mouth until they hatch. This is called mouth brooding. If you look closely, you can see the eggs inside the mouth of the cardinalfish pictured here. Answer: mouth brooding

SOLUTION: Some species of fish carry their fertilized eggs in their mouth until they hatch; this is called what?

PROBLEM: 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

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

PROBLEM: Passage: Hundreds of species of birds have gone extinct as a result of human actions. A well-known example is the passenger pigeon. It was once the most common bird in North America, but over-hunting and habitat destruction led to its extinction in the 1800s. Habitat destruction and use of the pesticide DDT explain the recent extinction of the dusky seaside sparrow. This native Florida bird was declared extinct in 1990. Answer: human actions

SOLUTION:
Which single most factor is responsible for the extinction of hundreds of species of birds?