The correct answer is: d) Nepal.
Nepal invaded and occupied Sikkim for a period in the 18th century. The invasion was led by Prithvi Narayan Shah, the founder of the modern Nepali state. Shah’s forces invaded Sikkim in 1770 and captured the capital, Gangtok. The Sikkimese were forced to sign a treaty of submission to Nepal in 1772. Nepali rule over Sikkim lasted for over 50 years. In 1826, the British East India Company intervened and forced Nepal to withdraw from Sikkim. Sikkim became a British protectorate in 1861.
Bhutan is a landlocked country in the Eastern Himalayas. It is bordered by China to the north and India to the south, east, and west. Bhutan is a member of the United Nations, the South Asian Association for Regional Cooperation, and the Non-Aligned Movement.
Tibet is a region in East Asia, mostly in the Himalayas. It is the traditional homeland of the Tibetan people and is now a part of the People’s Republic of China. Tibet is a mountainous region with a high altitude. The capital of Tibet is Lhasa.
Cooch Behar is a former princely state in India. It was located in the present-day state of West Bengal. Cooch Behar was founded in the 16th century by the Koch dynasty. The state was annexed by British India in 1839.
The answer to the question is d) Nepal.