Concept:Indian Railways has several long-distance routes. The longest rail route in India is measured by distance between the two farthest stations on the mainland.Explanation:The longest rail route in India is from Dibrugarh in Assam to Kanyakumari in Tamil Nadu. This route is covered by the Vivek Express. The distance is 4,233 km. The journey takes about 80 hours and 15 minutes. It connects the northeastern part of India to the southernmost tip of the mainland. The train was started in 2013 on the 150th birth anniversary of Swami Vivekananda. It is also the 24th longest train route in the world.Answer:The largest rail route in India is Dibrugarh to Kanyakumari (Option B).