What maintenance function may the holder of a GMDSS Radio Operator license perform, or supervise the performance of, on an Inmarsat-C SES?

The correct answer pertains specifically to routine maintenance that involves cleaning physical components of the Inmarsat-C Ship Earth Station (SES) to ensure optimal performance. The maintenance function of removing stack deposits and other debris from the antenna is important because any obstructions or buildup can cause signal degradation, resulting in poor communication quality. This task falls under the scope of necessary maintenance that a GMDSS Radio Operator can perform or supervise.

Other options, while they may seem relevant to operational efficiency or maintenance of the Inmarsat-C SES, involve more complex functions that require different levels of training or technical qualifications. For instance, adjusting the station's Effective Isotropic Radiated Power (EIRP) and tuning synthesizers generally require specialized knowledge and certification beyond what is typically granted to a GMDSS Radio Operator. Similarly, entering Azimuth and Elevation values or adjusting sophisticated technical settings are tasks that demand a deeper understanding of technical specifications and operations, aligning more with the responsibilities of a certified technician or engineer.