The correct answer is (a) Pithoragarh.
Lipulekh Pass is a high mountain pass in the Himalayas on the border between India and Nepal. It is located in the Pithoragarh district of Uttarakhand, India. The pass is at an elevation of 5,065 metres (16,620 ft) above sea level. It is a popular trekking destination and is also used as a trade route between India and Nepal.
The other options are incorrect because:
(b) Uttarkashi is a district in the Garhwal region of Uttarakhand, India. The district is located in the Garhwal Himalayas and is home to several high mountain passes, including the Nanda Devi Pass and the Pindari Pass.
(c) Rudraprayag is a district in the Garhwal region of Uttarakhand, India. The district is located in the Garhwal Himalayas and is home to several high mountain passes, including the Kedarnath Pass and the Badrinath Pass.
(d) Bageshwar is a district in the Kumaon region of Uttarakhand, India. The district is located in the Kumaon Himalayas and is home to several high mountain passes, including the Chaukori Pass and the Milam Pass.