The correct answer is B) not asking subjects to agree to participate without first informing them of the nature of the study and possible risks and benefits.
Explanation:
Clinical trials often involve testing treatments such as new vaccines, medicines or therapies. Moreover, these can have different positive or negative effects on participants of the trial. Due to this, one of the basic principles to follow ethical standards for this type of medical research is being completely honest with participants, which includes explaining to them the purpose of the trial, possible risk and also positive benefits.
This is important because in this way participants can make an informed decision on whether to participate or not in the trial which is part of consent. Thus, ethical standards for clinical trials include "not asking subjects to agree to participate without first informing them of the nature of the study and possible risks and benefits".
