The correct answer is: A. NH-1
Grand Trunk Road is the oldest and longest national highway in India. It is a part of National Highway 1, which runs from Varanasi in Uttar Pradesh to Kanyakumari in Tamil Nadu. The highway is 2,500 kilometers long and passes through 13 states. It was built by Sher Shah Suri in the 16th century and is one of the most important highways in India.
Option B is incorrect because NH-2 is a national highway in India that runs from Delhi to Kolkata. It is 1,483 kilometers long and passes through the states of Haryana, Uttar Pradesh, Bihar, Jharkhand, and West Bengal.
Option C is incorrect because NH-8 is a national highway in India that runs from Delhi to Mumbai. It is 1,394 kilometers long and passes through the states of Haryana, Rajasthan, Gujarat, and Maharashtra.
Option D is incorrect because NH-10 is a national highway in India that runs from Delhi to Agra. It is 206 kilometers long and passes through the states of Haryana and Uttar Pradesh.