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

Q: Exotic species are also called invasive species because they threaten other species.

A: Why are exotic species also called invasive species?
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Q: Fungi is the major cause of disease in agricultural crops.

A: What is the major cause of disease in agricultural crops?
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Q: The color of the powder of a mineral is called streak.

A:
What is the color of the powder of a mineral called?
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