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

[Q]: Negative growth rate results when birth rates fall even lower than death rates.
[A]: What results when birth rates fall even lower than death rates?


[Q]: Smaller size of ring will a summer drought cause in a tree.
[A]: What size of ring will a summer drought cause in a tree?


[Q]: Planets are held by the force of gravity in elliptical orbits around sun.
[A]:
Planets are held by the force of gravity in elliptical orbits around what?