The correct answer is: C. NH-73A
NH-73A is a national highway in India that runs from Shimla to Narkanda in Himachal Pradesh. It is a 4-lane highway with a length of 52.8 km. It is the shortest national highway in Himachal Pradesh.
NH-1A is a national highway in India that runs from Delhi to Leh in Ladakh. It is a 2-lane highway with a length of 476 km. It is the longest national highway in Himachal Pradesh.
NH-72 is a national highway in India that runs from Chandigarh to Manali in Himachal Pradesh. It is a 2-lane highway with a length of 252 km.
NH-20A is a national highway in India that runs from Una to Mandi in Himachal Pradesh. It is a 2-lane highway with a length of 170 km.