Correct Answer:
A. Fazl Hussain
The correct answer is Fazl Hussain. The Unionist Party in British India was primarily a political party in the Punjab province, founded by Sir Fazl-i-Hussain in 1923. It represented the interests of the rural population, particularly the Muslim, Hindu, and Sikh landlords and peasants, aiming to promote communal harmony and economic development in the region. M.A. Jinnah was the leader of the All-India Muslim League, a distinct political entity. Sikandar Hayat Khan was a prominent leader of the Unionist Party but not its founder. Therefore, options B, C, and D are incorrect.