Ladarcha fair is held annually at

Lahaul and Spiti
Mandi
Solan
Una

The correct answer is: A. Lahaul and Spiti.

The Ladarcha fair is a traditional fair held annually in the Lahaul and Spiti district of Himachal Pradesh, India. It is a major cultural event for the people of the region, and attracts visitors from all over the country. The fair is held over a period of three days, and features a variety of cultural activities, including traditional dances, music, and folktales. There are also stalls selling local handicrafts and souvenirs. The Ladarcha fair is a great opportunity to experience the unique culture of Lahaul and Spiti, and to learn about the history and traditions of the region.

The other options are incorrect because:

  • Mandi is a district in Himachal Pradesh, but the Ladarcha fair is not held there.
  • Solan is a town in Himachal Pradesh, but the Ladarcha fair is not held there.
  • Una is a district in Himachal Pradesh, but the Ladarcha fair is not held there.