What is a key benefit of using a Mode C transponder?

The key benefit of using a Mode C transponder lies in its ability to provide altitude information, which assists air traffic control in verifying altitude readings for aircraft separation. When an aircraft is equipped with a Mode C transponder, it continuously broadcasts its altitude along with its identification, allowing air traffic controllers to track the aircraft's vertical position accurately. This is critical for maintaining safe distances between aircraft flying at different altitudes, thus enhancing overall safety in busy airspace.

The other options present potential benefits related to aviation, such as communication and automated functions, but they do not accurately describe the core function of a Mode C transponder. For instance, while weather information is important for pilots, it is not a function provided by a Mode C transponder. Similarly, controlling flight paths and direct communication with other aircraft are not capabilities associated with Mode C transponders, which focus primarily on altitude reporting for air traffic management.