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.

[Q]: Question: A person needing to cook up a burger, but lacking a grill or fire, can heat burger meat on? Answer: a vehicle engine.
[A]: a car engine is a source of heat

[Q]: Question: Two felled trees, split in twain, with the same number of rings, means they're the same? Answer: age.
[A]: a tree growing a tree-growth ring occurs once per year

[Q]: Question: It is easiest for a rose to grow? Answer: on tilled ground.
[A]:
the looseness of soil has a positive impact on a plant 's roots' growth in that soil