instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
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
answer:
What compounds contain only carbon and hydrogen?

question:
Passage: Immovable joints do not allow the bones to move at all. In these joints, the bones are fused together by very tough collagen. Examples of immovable joints include the joints between bones of the skull. You can see them in Figure below . Answer: immovable joints
answer:
The joints that are between the bones that make up the skull are what kind of joints?

question:
Passage: Courtship behaviors occur in many other species. For example, males in some species of whales have special mating songs to attract females as mates. Frogs croak for the same reason. Male deer clash antlers to court females. Male jumping spiders jump from side to side to attract mates. Answer: courtship
answer:
What type of behavior is frogs croaking or deer clashing antlers an example of?