Final answer:
The highest level of commercial navigation tracking is ADS-B, the most advanced and mandated system for aircraft tracking in many regions.
Step-by-step explanation:
The highest level of commercial navigation tracking is d) ADS-B, which stands for Automatic Dependent Surveillance-Broadcast. ADS-B is the most advanced system currently used for tracking aircraft. It provides air traffic controllers with real-time position data that is more accurate and reliable than the other methods listed, such as GPS, LORAN-C, and VOR/DME. ADS-B has become the standard for aviation navigation and surveillance and is mandated for use in many regions around the world due to its improved accuracy, integrity, and reliability.