The correct answer is C. Narrow gauge.
Narrow gauge is a type of railway track with a track gauge of less than 1,435 mm (4 ft 8 1â2 in), the standard gauge used in most of the world. Narrow gauge railways are often used in hilly areas because they are more flexible and can be built on steeper gradients than standard gauge railways.
Broad gauge is a type of railway track with a track gauge of more than 1,435 mm (4 ft 8 1â2 in). Broad gauge railways are often used in flat areas because they can carry more weight than standard gauge railways.
Meter gauge is a type of railway track with a track gauge of 1,000 mm (3 ft 3 3â8 in). Meter gauge railways are often used in countries where standard gauge railways are not practical, such as mountainous areas or countries with limited resources.
Special gauge is a type of railway track with a track gauge that is not standard, broad, or meter gauge. Special gauge railways are often used for specific purposes, such as mining or industrial railways.