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

Example Input: Passage: You can tell that this sponge is saturated with water because when it is squeezed, the water pours out. When something is saturated with water, it already holds as much water as possible. Compounds called hydrocarbons, which contain only carbon and hydrogen, can also be saturated, but not with water. Answer: hydrocarbons
Example Output: What compounds contain only carbon and hydrogen?

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

Example Input: Passage: A: When air temperature reaches the dew point, water vapor starts condensing. It may form dew (as on the spider web in the opening image), clouds, or fog. Dew forms on solid objects on the ground. Clouds form on tiny particles in the air high above the ground. Fog is a cloud that forms on tiny particles in the air close to the ground. Answer: condense
Example Output:
When the air temperature reaches the dew point, water vapor starts to do what?