The world's longest highway tunnel that connects Manali and Lahaul-Spiti throughout the year is _____.

Atal Tunnel

The correct answer is Option (2) → Atal Tunnel

The World’s longest Highway tunnel — Atal Tunnel (9.02 Km) has been built by Border Road Organisation. This tunnel connects Manali to Lahaul-Spiti valley throughout the year. Earlier the valley was cut off for about 6 months each year owing to heavy snowfall. The Tunnel is built with ultra-modern specifications in the Pir Panjal range of Himalayas at an altitude of 3000 metres from the Mean Sea Level (MSL).