Given a scientific question, generate a correct answer to it.

[EX Q]: In atherosclerosis, thickening of an arterial wall due to this can restrict blood flow through the artery?
[EX A]: plaque formation

[EX Q]: To undo the tarnish on copper pennies, you can place them in what liquid?
[EX A]: vinegar

[EX Q]: In animals, what process occurs only in germ cells, which are in the ovaries or testes?
[EX A]:
meiosis