The correct answer is: C. SOR
The ruling gradient of the division is mentioned in the SOR (Statement of Route). The SOR is a document that provides information about the route, including the ruling gradient, the maximum speed, and the minimum passing distance. The SOR is used by train drivers to plan their journey and to ensure that they comply with the safety regulations.
SWR stands for Standard Width Gauge. It is the standard gauge for railways in India. The SWR is 5 feet 6 inches (1.676 meters).
WTT stands for Working Time Table. It is a document that provides information about the train services that are operated on a particular railway line. The WTT includes information about the train numbers, the departure and arrival times, and the stops that are made.
None of these is the correct answer because the ruling gradient of the division is mentioned in the SOR (Statement of Route).