The correct answer is: a) Introduce democratic reforms in Sikkim.
The Tripartite Agreement of 1973 was signed by India, Sikkim, and the Chogyal of Sikkim. The agreement led to the merger of Sikkim with India and the end of the Chogyal’s rule. The agreement also provided for the introduction of democratic reforms in Sikkim.
Option b) is incorrect because the agreement did not grant Sikkim special status within India. Sikkim became a full-fledged state of India after the merger.
Option c) is incorrect because the agreement did not partition Sikkim along ethnic lines. Sikkim remained a single state after the merger.
Option d) is incorrect because the agreement did not restore the Chogyal’s power. The Chogyal was deposed after the merger and Sikkim became a full-fledged state of India.