The correct answer is (b) Chamoli.
The Valley of Flowers is a high-altitude meadow located in the Garhwal Himalayas in the Indian state of Uttarakhand. It is a UNESCO World Heritage Site and is known for its diverse plant life, including over 300 species of flowers. The valley is located in the Chamoli district of Uttarakhand, and is accessible by trekking from the village of Govindghat.
The other options are incorrect. Uttarkashi is a district in the Garhwal Himalayas in the Indian state of Uttarakhand. Pauri Garhwal is a district in the Garhwal Himalayas in the Indian state of Uttarakhand. Rudraprayag is a district in the Garhwal Himalayas in the Indian state of Uttarakhand.
The Valley of Flowers is a popular tourist destination, and is open to visitors from June to October. The best time to visit is during the monsoon season, when the flowers are in bloom.