The correct answer to the question is option 4: Cornwallis. The Indian Civil Service was introduced during the period of Lord Cornwallis, who served as Governor General of India from 1786 to 1793. The Indian Civil Service was established in 1786 as a part of Cornwallis` administrative reforms. It aimed to create a professional bureaucracy for the efficient governance of British India. Under this service, British civil servants were recruited to administer various aspects of the colonial administration, including revenue collection, judicial proceedings, and law enforcement. The adoption of the Indian Civil Service played a significant role in consolidating British control over India by bringing in efficient and impartial administration.