The body shape of a Kalimma butterfly resembles a leaf. How did a similar body shape form in a butterfly?

1) The occurrence of a mutation that caused the shape of the body of a butterfly in the form of a leaf
2) Preservation by natural selection of individuals with a similar body shape, since they were less noticeable against the background of the environment and were less likely to be eaten by predators
3) Individuals with a similar body shape more often survived, multiplied and spread – as a result, the trait was fixed in a series of generations