The correct answer is: C. SH-16
SH-16 is the longest state highway in Himachal Pradesh. It is a 470-km-long highway that connects Shimla to Leh in Ladakh. The highway passes through the towns of Kullu, Manali, Leh, and Srinagar.
SH-13 is a 270-km-long highway that connects Shimla to Mandi. SH-14 is a 250-km-long highway that connects Shimla to Solan. SH-17 is a 200-km-long highway that connects Shimla to Chamba.
SH-16 is a well-maintained highway with a good surface. The highway is open throughout the year, but it is advisable to check the weather conditions before traveling. The highway is a popular tourist destination and offers stunning views of the Himalayas.