The correct answer is: A. T/1408
An authority to proceed without line clear (APWLC) is a document that allows a train to proceed without having to wait for a line clear signal. It is used in situations where there is a risk of a train being delayed or stopped due to a signal failure or other obstruction.
The APWLC is issued by a train dispatcher and is valid for a specific period of time. The dispatcher will specify the route that the train must take and the speed that it must travel. The train must also have a qualified crew on board.
The APWLC is a safety measure that helps to ensure that trains can operate safely and efficiently. It is important to note that the APWLC does not authorize a train to violate any other safety rules.
Option B, T/A1408, is not a valid form number for an APWLC. Option C, T/B1408, is also not a valid form number for an APWLC. Option D, None of these, is also not the correct answer.