Which two advances in technology significantly contributed to the growth of unmanned aircraft?

The selection of GPS navigation and closed-loop stabilized flight control systems as significant contributors to the growth of unmanned aircraft is well-founded. GPS technology has revolutionized navigation for unmanned systems, allowing for precise location tracking, waypoints navigation, and autonomous flight planning. This level of accuracy in spatial awareness is crucial for the safe and effective operation of unmanned aerial vehicles (UAVs), enabling them to follow pre-planned routes and perform complex missions without human intervention.

Concurrently, closed-loop stabilized flight control systems are essential for maintaining stable flight. These systems utilize sensors to detect changes in the aircraft's position and automatically adjust controls to counteract any disturbances. This technology enhances the maneuverability and responsiveness of unmanned aircraft, making them capable of performing in various environmental conditions and during dynamic missions such as surveillance or delivery.

While the other options may include technologies relevant to the broader field of aviation or engineering, they do not specifically highlight the critical advancements that have directly impacted the design and function of UAVs as significantly as GPS and flight control systems have.