Which of the following terms is defined as a back-up power source that provides power to radio installations for conducting Distress and Safety communications?

The term defined as a back-up power source that provides power to radio installations for conducting Distress and Safety communications is "Reserve Source of Energy" (RSE). This designation is specifically used in maritime communication systems to refer to a power supply that ensures communication equipment remains operational in emergency situations. The RSE is critical in ensuring that vessels can send and receive distress alerts and safety communications even when the primary power source fails, thereby maintaining safety at sea.

The other choices represent various types of generators or power sources, but they do not align with the specific terminology recognized for supporting radio installations in emergencies. For instance, while an Emergency Diesel Generator (EDG) is indeed a back-up power source, it does not universally encompass all forms of reserve energy used for communications, which is specifically defined under RSE. The Reserve Source of Diesel Power (RSDP) and Emergency Back-up Generator (EBG) also refer more closely to specific types of generators rather than the broader concept of a reserve energy source that accommodates radio communication needs, particularly in distress scenarios.