I believe the answer is Shaping.
Shaping is a reinforcement technique which use a reward that given gradually after the subject is showing a certain desired traits.
On parakeets, this could be done by giving them a food reward everytime they move their head closer to the place where we want it to be (closer to your cheek)
The answer is A an in-group-bias. Favoring ones own group rather than others.
The African Americans in the north during the mid 1800's were very poor. Most died from illnesses and natural causes. It was a very harsh time for them.
You explain the sentence with the evidence from the text to support your answer
i thinks its hazard signs