Q: Three of these railways, Darjeeling Himalayan Railway, Nilgiri Mountain Railway, and Kalka -- Shimla Railway have been collectively designated as a UNESCO World Heritage Site, also named as "Mountain Railways of India", while the fourth railway, Matheran Hill Railway is in tentative list of UNESCO World Heritage Site. These all are narrow-gauge railways. The Nilgiri Mountain Railway is also, the only rack railway in India.\n\nAnswer this question based on the passage: three mountain railway lines in india which has been designated as unesco world heritage site? Let's give stream of consciousness first:
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To answer the above question, the relevant sentence is: Three of these railways, Darjeeling Himalayan Railway, Nilgiri Mountain Railway, and Kalka -- Shimla Railway have been collectively designated as a UNESCO World Heritage Site, also named as "Mountain Railways of India", while the fourth railway, Matheran Hill Railway is in tentative list of UNESCO World Heritage Site. Therefore, the final answer is Darjeeling Himalayan Railway , Nilgiri Mountain Railway , and Kalka -- Shimla Railway.
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