The correct answer is A. 107 km.
The Kalka-Shimla Railway is a narrow-gauge mountain railway in India. It is a UNESCO World Heritage Site and one of the most popular tourist destinations in India. The railway was built between 1891 and 1903 and is one of the steepest railways in the world. It has 103 tunnels and 864 bridges. The total length of the railway is 107 km.
Option B is incorrect because the total length of the railway is 107 km, not 98 km.
Option C is incorrect because the total length of the railway is 107 km, not 333 km.
Option D is incorrect because the total length of the railway is 107 km, not 96 km.