The most beautiful valley of Kinnaur district is

Sangla
Har ki Doon
Kangra
Pin

The correct answer is: A. Sangla

Sangla Valley is a beautiful valley in the Kinnaur district of Himachal Pradesh, India. It is located in the Himalayas, and is surrounded by snow-capped mountains. The valley is home to a number of villages, and is a popular tourist destination.

Har Ki Doon is a valley in the Garhwal Himalayas, in the Indian state of Uttarakhand. It is located in the Chamoli district, and is about 200 kilometers from the state capital, Dehradun. The valley is a popular tourist destination, and is known for its scenic beauty.

Kangra Valley is a valley in the Kangra district of Himachal Pradesh, India. It is located in the foothills of the Himalayas, and is about 200 kilometers from the state capital, Shimla. The valley is home to a number of towns and villages, and is a popular tourist destination.

Pin Valley is a valley in the Lahaul and Spiti district of Himachal Pradesh, India. It is located in the Himalayas, and is about 500 kilometers from the state capital, Shimla. The valley is home to a number of villages, and is a popular tourist destination.

Sangla Valley is the most beautiful valley of Kinnaur district because of its scenic beauty and its rich cultural heritage. The valley is home to a number of villages, each with its own unique culture and traditions. The valley is also home to a number of temples and monasteries, which are important centers of Buddhist pilgrimage.