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

[EX Q]: Passage: Not all wetlands are alike, as you can see from Figure below . Wetlands vary in how wet they are and how much of the year they are soaked. Wetlands also vary in the kinds of plants that live in them. This depends mostly on the climate where the wetland is found. Types of wetlands include marshes, swamps, and bogs. Answer: wetlands
[EX A]: Marshes, swamps, and bogs are types of what?

[EX Q]: Passage: If water is so simple, why is it special? Water is one of the few substances that exists on Earth in all three states of matter. Water occurs as a gas, a liquid and a solid. You drink liquid water and use it to shower. You breathe gaseous water vapor in the air. You may go ice skating on a pond covered with solid water ice in the winter. Answer: three matter states
[EX A]: In how many states does water exist on earth?

[EX Q]: Passage: Immovable joints allow no movement because the bones at these joints are held securely together by dense collagen. The bones of the skull are connected by immovable joints. Answer: immovable
[EX A]:
The bones of the skull are connected by what type of joints?