Answer: option c voluntary participation
Explanation: in voluntary participation, humans involved in research are allowed to exercise full measure of their will to participate in a research
without being coerced or forced. It is a free will participation. Voluntary participation I also the given of a full consent by individuals to participate or being used as a subject in an experiment. Ethically, the standard taken for someone to participate in an experiment is that of full concent given by the person( voluntary participation) and no harm to
research participants because at times some experiment are dangerous and some outcomes cannot be predictions.