Final answer:
The CTAF/MULTICOM frequency for Garrison Airport can be obtained from official aviation resources such as the A/FD or sectional charts, which provide published communication frequencies for pilots.
Step-by-step explanation:
To determine the CTAF/MULTICOM frequency for Garrison Airport, one would typically refer to the airport's published communication frequencies in a resource such as the Airport/Facility Directory (A/FD) or on sectional charts. CTAF stands for Common Traffic Advisory Frequency and is used by pilots to self-announce their position and intentions when flying to or from an airport without an operating control tower, or when the tower is closed. MULTICOM is a term used for a frequency designated for the purpose of carrying out advisory practices while not in contact with air traffic control. The correct MULTICOM frequency can only be verified through these official aviation resources. Without access to these resources, it is not possible to definitively answer which frequency is used for Garrison Airport.