Final answer:
Decentralized materiel support (DMS) personnel are required to notify the flightline expediter of all back ordered parts.
Step-by-step explanation:
The correct answer is a. Decentralized materiel support (DMS) personnel. According to AFI 21-101, decentralized materiel support (DMS) personnel are required to notify the flightline expediter of all back ordered parts. These personnel, who are responsible for managing and distributing the necessary materiel for operations, play a crucial role in ensuring that adequate supplies are available on the flightline. By notifying the flightline expediter about any back ordered parts, they can help expedite the procurement process and minimize disruptions to operations.