Informed consent

allows you to quit an experiment at any time
is not a necessary step for all experiments
is a requirement only if potential harm will happen
is only a requirement for non-school experiments.

The correct answer is A.

Informed consent is important as it provides participants with all the detailed information on the study so that they can make an informed, voluntary and rational decision to participate in the study. It also gives you the right to quit an experiment at any time. All participants taking place in research have the right to withdraw at any time and by giving their informed consent to participate they are acknowledging this right and also it's for legal reasons for the researchers.

i agree d is most definitely correct!