The correct answer is: d) All of the above.
The British Political Officer stationed in Gangtok played a role in advising the Chogyal, mediating disputes, and overseeing trade and infrastructure.
The British Political Officer was the representative of the British government in Sikkim. The Chogyal was the hereditary ruler of Sikkim. The British Political Officer was responsible for advising the Chogyal on matters of state and for mediating disputes between the Chogyal and his subjects. The British Political Officer was also responsible for overseeing trade and infrastructure in Sikkim.
The British Political Officer was a powerful figure in Sikkim. The Chogyal was not allowed to make any important decisions without the approval of the British Political Officer. The British Political Officer also had the power to dismiss the Chogyal.
The British Political Officer was withdrawn from Sikkim in 1975. This was after Sikkim became an Indian state.