Which Logix5000 controller mode is available only through a computer and cannot be set directly by a physical keyswitch?

The correct mode that is only available through a computer and cannot be set directly by a physical keyswitch is Remote Test Mode. This mode allows for testing and debugging of the application without fully switching to a run mode. By using Remote Test Mode, you can observe and analyze the program execution while the process continues to run, making it particularly useful for diagnostics and validation tasks.

Remote Test Mode is intended for situations where you're interfacing with specific software tools and environments, making it necessary to access it via a PC connection rather than via a physical keyswitch. In contrast, other modes like Program Mode, Run Mode, and Remote Mode can be accessed directly using physical controls on the controller, providing more straightforward operation directly from the hardware interface.