Explanation:

The Indian Railways have brought in a lot of innovation and new technologies in the Railways since Independence. All the options mentioned have been incorporated by the Railways.

Gauge conversion is the change of one railway track gauge to another. This may be required if loads are too heavy for the existing track gauge or if rail cars are of a broader gauge than the existing track gauge. Gauge conversion may become less important as time passes due to the development of variable gauge systems, also called Automatic Track Gauge Changeover Systems.

A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electric railways use either electric locomotives (hauling passengers or freight in separate cars) or electric multiple units (passenger cars with their own motors). Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines, but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers.

Automatic block signaling is a railroad communications system that consists of a series of signals that divide a railway line into a series of sections, or "blocks". The system controls the movement of trains between the blocks using automatic signals