The wild carrot sprigs that starlings add to their nests function

The wild carrot sprigs that starlings add to their nests
  function
  a. as a form of camouflage against predators.
  b. as a form of insulation.
  c. to repel parasites.
  d. to prevent other birds from using the nest.
  e. in ways that are currently unknown.

Question 2

An example(s) that illustrate(s) natural selection
  acting on behavioral traits that benefit individuals
  include(s)
  a. the effect of oxytocin on vole reproductive
  behavior.
  b. the different responses of young coastal and
  inland garter snakes to banana slugs.
  c. courtship behavior in sage grouses.
  d. the nest-decorating behavior of starlings.
  e. all of these.