Answer: A. Neither Wendy nor Sam had a duty to aid the divers in peril.
Step-by-step explanation:
Sam and Wendy were simply customers of Mike in this scenario and so could not be reasonable expected to take over his duties to oversee the dive which he initiated and was aware of the risks of.
They therefore did not have a duty to aid the other divers especially given the fact that they did not know the risks involved in diving in that particular area. The only person who had an actual duty to rescue the divers is the company or person that took the people on the dive which in this case was Mike.