In this task, you are given a question and a corresponding answer. Your task is to generate a fact statement that is useful in answering the given question.

[EX Q]: Question: Someone stranded in the Sahara can potentially save their life with a? Answer: prickly plant's trunk.
[EX A]: a cactus stem is used for storing water

[EX Q]: Question: Trees grow growth-rings one time each year; so which of these is correct? Answer: a tree with nine rings is nine years old.
[EX A]: a tree growing a tree-growth ring occurs once per year

[EX Q]: Question: friction is used for stopping a vehicle by? Answer: squeezing.
[EX A]:
friction is used for stopping a vehicle by brakes