With the Exception of Prosthodontics,why Is It Generally Not Recommended

With the exception of prosthodontics,why is it generally not recommended to schedule more than two appointments in advance?

A) It is easier for the dentist to remember the appointments.
B) With less than two appointments, the dentist's schedule becomes overbooked.
C) With less than two appointments, time is not available for new patients and emergencies.
D) There is a greater chance of a patient missing an appointment if it is scheduled too far in advance.