Convection in the mantle is the answer
Answer:
Self-Serving Bias
Explanation:
Marty just found out that he failed his History GR. He believes that he did poorly on the test because the instructor asked unfair questions and that he had a lot of other activities going on. Marty's beliefs about why he failed are an example of Self-Serving Bias
By using the wheel, mankind gained the ability to work more efficiently and travel more quickly. Besides its use in transportation, the wheel went on to become the basic principle behind almost every mechanical device.
Serf is the correct answer.
Under feudalism, serfs (also known as peasants) represented the lowest class in the system. Even though they were not slaves neither own the land the worked in, they were bound to it. Serfs were required to give a part of their harvest to the person who actually owned te land. In return, these serfs were able to keep their own subsistence and were protected against bandits, thieves and possible injustices.
