Name the longest highway single-tube tunnel that reduces the travel time and overall distance between Manali and Keylong.

Correct option is A

The correct answer is (a) Atal Tunnel.
 Atal Tunnel is the longest highway single-tube tunnel in the world, located in the state of Himachal Pradesh, India.
 It reduces the travel time and overall distance between Manali and Keylong by bypassing the Rohtang Pass.
 The tunnel is 9.02 kilometers long and is situated at an altitude of about 3,000 meters above sea level.
 It was inaugurated on October 3, 2020, and is named after the former Prime Minister of India, Atal Bihari Vajpayee.
Information Booster
Natuwadi Tunnel:
 Located in Maharashtra, India, on the Konkan Railway line.
 It is 4.3 kilometers long.
Karbude Tunnel:
 Also part of the Konkan Railway, located in Maharashtra, India.
 It is 6.5 kilometers long and was the longest tunnel on the Konkan Railway until the completion of the Pir Panjal Railway Tunnel.
Jawahar Tunnel:
 Located in Jammu and Kashmir, India.
 It is 2.85 kilometers long and connects Banihal and Qazigund, facilitating travel between Jammu and Srinagar.