The correct answer is A: An evaluation must always be performed. When operating an amateur station on 80 meters, an RF exposure evaluation must always be performed. There are no automatic exemptions for 80-meter operation. FCC rules require RF exposure evaluation for amateur stations, and 80-meter operation is not exempt. Even low-power 80-meter stations require evaluation, though the evaluation may show that exposure is below limits and no mitigation is needed. The evaluation is required to determine whether MPE limits are exceeded and what mitigation (if any) is needed. There's no blanket exemption for 80 meters based on power level, mode, or other factors. The evaluation must be performed, though it may conclude that no action is needed if exposure is below limits.