Which among the following National Highway routes is the longest?

Correct Option (c):

The Kolkata–Hajira route, historically designated as National Highway 6 (NH-6), extended from Kolkata in West Bengal to Hajira in Gujarat. This route covered a distance of over 1,900 km, making it the longest among the options provided. It served as a significant east-west corridor, traversing multiple states including West Bengal, Jharkhand, Odisha, Chhattisgarh, Maharashtra, and Gujarat. Under the rationalized numbering system, segments of this route have been renumbered as parts of NH-16 and NH-53, continuing to form a crucial component of India's major highway network, including the Golden Quadrilateral and the East-West freight corridor.

Incorrect Options:

• Agra–Mumbai (via old NH-3) had an approximate length of 1,200 km.
• Chennai–Thane had an approximate length of 1,300 km.
• Pune–Machilipatnam had an approximate length of 900 km.

These routes were considerably shorter than the Kolkata–Hajira corridor at the time the question was posed.