Angola, one of Nigeria’s trading partner countries, is trying to protect its domestic oil refineries from competition. To do so, it limits the amount of refined oil that can be imported from other countries. Which type of trade barrier is being described?

A.
embargo

B.
specialization

C.
tariff

D.
quota

Francine, a college freshman, has agreed to participate in a psychology research study. before she begins her participation, she reads a statement written by the researcher explaining the purpose of the research and the potential risks of participation. it also explains that francine is free to withdraw from the research at any time. in providing francine with this statement, the researcher has followed the ethical guidelines of for participants.