The correct answer is: a) China (Tibet).
The Nathu La Pass is a high mountain pass in the Himalayas on the border between India and China. It is located in the Sikkim state of India and the Tibet Autonomous Region of China. The pass is 4,310 meters (14,140 feet) above sea level and is open for trade between India and China from May to November.
The Nathu La Pass was closed in 1962 after the Sino-Indian War. It was reopened in 2006 as part of a thaw in relations between India and China. The pass is a major trade route between India and China, and it is used to transport goods such as tea, spices, and textiles.
The other options are incorrect because they are not countries that share a border with India. Nepal is located to the west of India, Bangladesh is located to the east of India, and Bhutan is located to the north of India.