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

[Q]: In the lungs, oxygen diffuses out of the alveoli and into capillaries.
[A]: In the lungs, oxygen diffuses out of the alveoli and into where?


[Q]: A student should use a balance to compare the masses of two small rocks.
[A]: Which tool should a student use to compare the masses of two small rocks?


[Q]: A(n) esker is a winding ridge of sand deposited by a stream of meltwater called.
[A]:
What is a winding ridge of sand deposited by a stream of meltwater called?