Final answer:
AFMC - Air Force Materiel Command is the MAJCOM that developed the Type IV hydrant fueling system, which is essential for rapid aircraft fueling at military airfields.
Step-by-step explanation:
The major command (MAJCOM) that developed the Type IV hydrant system is D) AFMC - Air Force Materiel Command. The Type IV hydrant system is an aviation fueling system used extensively at military airfields. It allows for rapid fueling of aircraft, reducing the amount of time aircraft need to spend on the ground between missions. This infrastructure is critical for maintaining an efficient and ready air force, as it supports the quick turnaround of aircraft during operations.