Which among the following National Highway routes is the longest?

Comparing the route lengths given in the provided sources shows that the Kolkata–Hajira route is the longest among the options. Kolkata–Hajira is listed at about 1,946 km, while Chennai–Thane is around 1,235 km and Agra–Mumbai about 1,161 km — all three figures are reported together in the same source. The Pune–Machilipatnam route is substantially shorter, approximately 841 km according to the other route listing. Therefore, Kolkata–Hajira (option 3) is the longest of the four given highway routes based on the cited route lengths.