Final answer:
The least part of obtaining informed consent is explaining the hypothesis to the participants.
Step-by-step explanation:
The least part of obtaining informed consent is A. explaining the hypothesis to the participants. Informed consent involves providing participants with a clear understanding of what to expect during an experiment, including potential risks and implications, as well as ensuring their participation is voluntary and their data will remain confidential. However, explaining the hypothesis is not a necessary component of obtaining informed consent.