The railway line from Kalka to Shimla was built in

The correct answer is: A. 1903

The Kalka–Shimla Railway is a narrow-gauge mountain railway in the Indian state of Himachal Pradesh. It is a UNESCO World Heritage Site. The railway was built between 1898 and 1903 by the British Raj to connect the hill station of Shimla with the plains of India. The railway is 96 km (60 mi) long and has 103 tunnels and 864 bridges. It is one of the steepest railways in the world, with a maximum gradient of 1 in 33.

The railway is a popular tourist attraction. It is also used by locals to travel between Kalka and Shimla. The railway is operated by the Indian Railways.

Here is a brief explanation of each option:

• Option A: 1903 is the correct answer. The railway was built between 1898 and 1903.
• Option B: 1904 is incorrect. The railway was built between 1898 and 1903.
• Option C: 1902 is incorrect. The railway was built between 1898 and 1903.
• Option D: 1898 is incorrect. The railway was built between 1898 and 1903.