Final answer:
The potential source of risk is the staff.
Step-by-step explanation:
The potential source of risk when staff at the indoor climbing gym have never climbed before is staff.
Staff members who have never climbed before may not have the necessary experience, knowledge, or skills to recognize and mitigate risks associated with climbing activities. As a result, they may not be able to provide proper guidance or respond effectively to emergencies. This lack of expertise increases the chances of accidents and injuries for both staff and climbers.