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

[EX Q]: Passage: In the solar system, the planets orbit around the Sun. The Sun and each of the planets of our solar system are round. Earth is the third planet from the Sun. It is one of the inner planets. Jupiter is an outer planet. It is the largest planet in the solar system at about 1,000 times the size of Earth. The Sun is about 1,000 times bigger than Jupiter! ( Figure below ). Answer: the sun
[EX A]: What do the planets orbit around in the solar system?

[EX Q]: 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
[EX A]: Some species of fish carry their fertilized eggs in their mouth until they hatch; this is called what?

[EX Q]: Passage: Recall that terrestrial biomes are defined by their climate. That's because plants and animals are adapted for certain amounts of temperature and moisture. However, would aquatic biomes be classified in the same way? No, that wouldn't make much senseall parts of an aquatic environment have plenty of water. Aquatic biomes can be generally classified based on the amount of salt in the water. Freshwater biomes have less than 1% salt and are typical of ponds and lakes, streams and rivers, and wetlands. Marine biomes have more salt and are characteristic of the oceans, coral reefs, and estuaries. Answer: amount of salt
[EX A]:
How are aquatic biomes often classified?