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

[Q]: People stopped adding lead to gasoline because of environmental pollution.
[A]: Why did people stop adding lead to gasoline?


[Q]: A volcano chain is formed by subduction of oceanic crust beneath a continental or oceanic plate.
[A]: What kind of chain is formed by subduction of oceanic crust beneath a continental or oceanic plate?


[Q]: Location is a factor in determining weight but not mass.
[A]:
What is a factor in determining weight but not mass?