Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Lipids are available to the body from three sources.

Answer: Lipids are available to the body from how many sources?

Question: An allele that's always expressed over another is a dominant allele.

Answer: What's the term for an allele that's always expressed over another?

Question: The frequency of a wave is the reciprocal of the period of the wave.

Answer:
The frequency of a wave is the reciprocal of what other attribute of the wave?