Final answer:
The proper security program for a Part 121 operator conducting scheduled operations in a Brasilia EMB 120 at a commercial airport and not using a Sterile Area is the Twelve-Five Standard Security Program (TFSSP).
Step-by-step explanation:
The proper security program for a Part 121 operator wanting to conduct scheduled air carrier operations with a Brasilia EMB 120 aircraft at a commercial service airport is the Twelve-Five Standard Security Program (TFSSP). This program is mandated for aircraft with a maximum takeoff weight of more than 12,500 pounds and is designed for operations that do not involve enplaning or deplaning passengers into a Sterile Area. Given that the Brasilia EMB 120 has a max takeoff weight of 26,378 pounds and seats less than 61 passengers, this would be the applicable security program. The TSA designed the TFSSP to provide a standardized level of security for smaller aircraft that do not use jet bridges directly into a Sterile Area.