Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Virtually all aquatic organisms depend directly or indirectly on protists for food.

A: Virtually all aquatic organisms depend directly or indirectly on what for food?
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Q: A mushroom is the fruiting body that occurs after two hyphae mate and form a mycelium with sporangia.

A: What is the fruiting body that occurs after two hyphae mate and form a mycelium with sporangia?
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Q: It is an inherited behavior that maintains the population statement explains why most salmon leave salt water and return to fresh water.

A:
Which statement explains why most salmon leave salt water and return to fresh water?
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