Answer:
This is an application of D. justice.
Step-by-step explanation:
Justice is an ethical principle from the Belmont Report. According to this principle, there should be a fair balance between the kinds of people who are the subjects of the research and the kinds of people who benefit from it. Therefore, if a researcher wants to study a specific ethnic group, he must first demonstrate that the problem under scrutiny truly affects that group. It is a matter of fairness, of justice. Otherwise, there should be no reason to study that specific group.