Answer : 1. "Kolkata"
Explanation :

Prime Minister Narendra Modi inaugurated Kolkata's unprecedented underwater metro train service, a milestone in India's infrastructure. The project, part of the East-West corridor of the Kolkata Metro, aims to boost connectivity between Howrah and Salt Lake. The Railway Ministry revealed that the 10.8-km east-west metro route includes both underground and elevated sections. This initiative marks a significant advancement in urban development and transportation for the capital of West Bengal.