Final answer:
The best time to discuss agency with the homeowner when showing a 'For Sale By Owner' home is when calling to arrange an appointment to show.
Step-by-step explanation:
The best time to discuss agency with the homeowner when showing a 'For Sale By Owner' home is a) When calling to arrange an appointment to show. This ensures that expectations are set upfront and both parties understand the role of the agent. By discussing agency during the appointment arrangement, the homeowner can make an informed decision about allowing the agent to show their home.