In this scenario, Rajneesh's doctor is primarily employing the principle of beneficence. Beneficence refers to the ethical obligation to act in the best interest of the patient by promoting their well-being and taking positive steps to help them. In discussing the benefits versus the risks of continuing medication during her pregnancy, the doctor is focusing on how to best support Rajneesh's health and well-being for both her and her developing baby.
While other principles, such as nonmaleficence (do no harm) and autonomy (respecting the patient's right to make informed decisions), are also relevant, the central focus of this interaction is on providing care that benefits Rajneesh and her pregnancy, aligning it most closely with beneficence.
Thus, the answer is:
B. beneficence