According to domestic air carrier duty rules, what is prohibited during a flight crewmember's required rest period?

During a flight crewmember's required rest period, they are prohibited from being assigned to any duty with the air carrier. This rule is established to ensure that flight crew members can adequately rest and recuperate before flying again. The primary purpose of a rest period is to allow crewmembers time to recover from fatigue and ensure they are mentally and physically prepared for their upcoming flights. Assignment to any duty during this time could compromise their ability to perform safely and effectively, leading to potential safety risks.

The other options involve activities that, while relevant to a crewmember's overall schedule, do not directly contravene the specific duty rules regarding required rest periods. Taking personal leave, attending training sessions, or scheduling flight operations can usually be managed outside the designated rest period as long as they do not interfere with the mandated rest requirement.