A __________ may be used per the manufacturer's instruction if the dope coating is found to have cracks but the fabric itself is still __________.

The correct choice indicates that a rejuvenator may be utilized according to the manufacturer's instructions if cracks are observed in the dope coating while the fabric remains airworthy. A rejuvenator is a special type of chemical compound designed to restore the flexibility and adhesion of the dope coating, effectively extending the life of the painted surface without requiring a complete reapplication.

The context of this process is crucial because even if the dope coating has developed cracks, if the underlying fabric is still structurally sound and maintains its airworthiness, it can often be salvaged. This is essential in maintaining the safety and integrity of the aircraft, as the fabric must still perform its role in supporting the structure and aerodynamics of the airplane.

This answer highlights a proactive approach to aircraft maintenance, allowing for repairs that are both practical and economical while ensuring compliance with safety standards. Rejuvenating the dope rather than replacing it can save time and resources, making it a favored option among maintenance professionals.