Which of the following is a characteristic of the electrical system?

The electrical system of the A320 is designed to operate automatically under normal circumstances, which is why the choice highlighting that system operation is typically automatic is correct. This means that various electrical components, such as the generators and batteries, coordinate their functions without requiring manual intervention from the flight crew during standard operations. This automatic management ensures that the aircraft's electrical needs are met efficiently and reliably, which is critical for maintaining safety and performance during flight.

In contrast, the other options misrepresent aspects of the A320's electrical system. Although the APU can supply power when needed, it does not strictly hold priority over engine generators; the system’s configuration allows for flexibility in power supply. Furthermore, while power sources can connect and interact, they are designed with isolation capabilities to ensure safety during maintenance or system faults. Lastly, the Integrated Drive Generators (IDGs) are not solely backed up by battery power; rather, they have their own primary sources, and battery power typically serves as a supplementary measure. This structured combination enhances the overall resilience and reliability of the A320's electrical system.