Which of the following studies requires IRB approval?

In research ethics, Institutional Review Board (IRB) approval is primarily required for studies that involve human subjects. This is due to the necessity of ensuring that the rights, welfare, and privacy of participants are protected throughout the research process. When a study involves living individuals, various ethical considerations arise, including informed consent, potential risks to the participants, and the way data is collected and handled. Thus, the requirement for IRB approval reflects the commitment to uphold ethical standards in research involving people.

In contrast, studies involving historical documents do not involve living individuals, making them exempt from IRB review since no human subjects are at risk. Similarly, studies that focus on animal behavior or do not interact with participants also do not necessitate IRB approval, as they either concern non-human subjects or do not involve direct engagement with individuals, thereby eliminating the need for oversight related to human subject ethics.