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

[Q]: A diet rich in calcium and vitamin d may reduce the risk of osteoporosis and related bone fractures.
[A]: A diet rich in calcium and what vitamin may reduce the risk of osteoporosis and related bone fractures?


[Q]: Comparing genome sequences provides clues to evolution and development.
[A]: Comparing what sequences provides clues to evolution and development?


[Q]: The number of neutrons can vary between atoms of the same element.
[A]:
The number of what subatomic particles can vary between atoms of the same element?