Do birds prefer red treats or blue treats?

Do birds prefer red treats or blue treats? Two different supplements, which have no effect on taste, are used on identical treats to produce a red treat or a blue treat. Volunteer birds are assigned randomly to either a red treat or a blue treat, and the researchers rate the treats based on how quickly the birds eat them. Is blinding demonstrated in the experiment?

 A.No, because the birds do not know the color treat they are getting

 B.Yes, by having the experimenter in a separate room pick one of the two containers at random and having a treat pulled from that container remotely

 C.No, because the birds know whether they are eating a red treat or a blue treat

 D.Yes, by having the statistician analyzing the results not know which bird sampled which treat

 E.Yes, by having the birds eat the treats out of the container, so they don't know the color of the treat they are eating