A. Beneficence: Beneficence requires researchers to maximize possible benefits while minimizing potential harm to participants. It involves careful risk–benefit analysis, protection from physical and psychological injury, and ongoing monitoring for adverse effects. This principle ensures that participant welfare remains a primary consideration throughout. B. Justice: Justice refers to fairness in the distribution of the burdens and benefits of research. It requires equitable selection of participants so that vulnerable populations are not exploited and no group is unfairly excluded from potential benefits. This principle guides inclusion criteria and recruitment practices. C. Respect for person: Respect for persons recognizes the autonomy of individuals and the need to provide additional protections for those with diminished autonomy. It underlies the requirement for informed consent, voluntary participation, and the right to withdraw without penalty. This principle safeguards individual decision-making capacity. D. All of the above: The foundational ethical framework for human subjects research incorporates beneficence, justice, and respect for persons as core principles. Together, they guide ethical study design, participant protection, and responsible conduct of research involving human participants.