What does a signal at a fixed location indicate concerning train movement?

A signal at a fixed location primarily indicates the conditions controlling train movement. Signals are crucial in railway operations as they convey important information to train operators regarding whether it is safe to proceed, to stop, or to prepare to take specific actions based on track conditions ahead.

For instance, a signal could be indicating that a track section is clear for movement, or it could show a restrictive signal, informing the operator to reduce speed or prepare for a stop due to varying track conditions, such as a train ahead or a section of track that is unsafe for travel. This ensures orderly and safe management of train movements and helps in preventing accidents.

The other options address aspects related to train operations but do not focus on the primary role of signals. Track maintenance schedules, train speed limits, and the duration of station stops are related to train operations but are not directly indicated by fixed signals in the same way that the current conditions impacting train movement are. Signals are designed specifically to monitor and control those movements, making option C the most relevant and correct choice.