Final answer:
The correct frequency to contact ATC at Elizabeth City CGAS RGL (ECG) airport is 124.375. It is important to use the designated frequency to ensure proper communication and safety.
Step-by-step explanation:
To operate a small Unmanned Aircraft System (sUAS) in the proximity of the Elizabeth City CGAS RGL (ECG) airport, you must contact Air Traffic Control (ATC). The correct frequency for contacting ATC at this airport is 124.375. Frequencies such as 122.95 and 120.50 are also used in aviation communications, but they are not the correct frequencies for this particular airport. It's crucial to use the right frequency to ensure safety and proper communication with ATC.