Answer/Explanation:
Natural selection - over time - selects for traits that improve fitness. A butterfly with wing coloration that looks like a hungry owl would certainly be a deterrent to their natural predators, such as smaller birds. This is because the owl is the predator of the smaller birds, and their instinct is to avoid the owl.
If a mutation arose that resulting in coloration that looked like an owl, (or at least slightly menacing) this would be beneficial to the butterfly, as it would be more camouflaged from predators. This means it would be more likely to reach reproductive age and pass the mutation onto its offspring, who would also have a competitive advantage.
Over time, this would lead to a population of butterflies with coloration that looks more and more owl-like .