Answer : 4. "Maharashtra"
Explanation :

PM Modi recently laid the foundation of India's longest and largest urban tunnel project in Mumbai. The Rs 16,000 crore Thane-Borivali Twin Tunnel Project operated by the Mumbai Metropolitan Region Development Authority will reduce travel time from 1 hour to just 12 minutes. Through the tunnel, vehicles from the Western Express Highway will be able to reach the Eastern Express Highway of Thane directly. To reduce the distance, the tunnel is being constructed under the Sanjay Gandhi National Park.