Who is issued Form D line 5 when a track is obstructed for maintenance?

The correct choice identifies that Form D line 5 is issued to the employee requesting the obstruction, operators, and approaching trains. This is crucial because Form D serves as a communication tool to inform relevant personnel about the status of the track, which is critical for safety during maintenance activities. By including operators and approaching trains, the form ensures that all parties are aware of the track's condition and can take necessary precautions to maintain safety, thereby preventing accidents or unsafe operations.

This approach aligns with safety protocols by ensuring comprehensive communication of track obstructions, vital for effective coordination among train crews and maintenance personnel. In contrast, issuing the form only to limited personnel, such as just the engineer or the employee in charge, would not provide the necessary situational awareness to all those who might interact with the affected track. Thus, the issuance to all relevant parties is necessary for the operational and safety integrity of train operations.