The correct answer is: A. T-1425
T-1425 is a train order that authorizes the movement of trains through an obstructed block section due to an accident. It is issued by the dispatcher and must be received by the train crew before they can proceed through the section.
B. T-369(3b)+P.No. is a train order that authorizes the movement of trains through a section that is closed for maintenance. It is issued by the dispatcher and must be received by the train crew before they can proceed through the section.
C. T/A 602 is a train order that authorizes the movement of trains through a section that is closed for inspection. It is issued by the dispatcher and must be received by the train crew before they can proceed through the section.
D. A simple memo is not a valid authority to proceed through an obstructed block section due to an accident.