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

[Q]: Three many families are known quarks divided into.
[A]: How many families are known quarks divided into?

[Q]: Pressure and vibration are examples of physical type of stimuli.
[A]: Pressure and vibration are examples of what type of stimuli?

[Q]: Benzoic acid type of acid is often used as a preservative for acidic foods such as fruit juices.
[A]:
What type of acid is often used as a preservative for acidic foods such as fruit juices?