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

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

[EX Q]: Gabbro is a dark dense rock that can be found in the oceanic crust.
[EX A]: Gabbro is a dark dense rock that can be found in what?

[EX Q]: The first line of defense includes mechanical, chemical, and biological other barrier.
[EX A]:
The first line of defense includes mechanical, chemical, and which other barrier?