The correct answer is option 4, NH 7. NH 7 is the longest National Highway in India, stretching over a distance of approximately 2,369 kilometers. It connects Varanasi in Uttar Pradesh to Kanyakumari in Tamil Nadu, passing through several major cities such as Nagpur, Hyderabad, and Bengaluru.

Option 1, NH 4, is also a significant National Highway but is not the longest. NH 4 runs from Thane in Maharashtra to Chennai in Tamil Nadu, covering a distance of about 1,235 kilometers.

Option 2, NH 5, is the second longest National Highway in India. It spans approximately 1,533 kilometers and connects Kolkata in West Bengal to Chennai in Tamil Nadu, passing through cities like Visakhapatnam and Bhubaneswar.

Option 3, NH 6, is a National Highway that runs from Hazira in Gujarat to Kolkata in West Bengal, covering a distance of about 1,841 kilometers. It is the third longest National Highway in the country.

Alert - correct answer should be option 4, NH 7.