The correct answer is D) introduce the teachings of the Qur'an.
The role of Muslim religious leaders in Africa was to: introduce the teachings of the Qur'an.
It couldn't be the four noble truths because the noble truths belong to Buddhism. Those are Buddhist teachings, and Islam is a completely different religion.
Indeed, the teachings of Qu'ran are based on the Five Pillars of Islam that are the following. The Shahada, that is the profession of the Muslim faith. The Salat, that is the daily prayers during different times of the day. The Zakat, that is sharing wealthy with the poor. The Saum, that is the fasting during the period of Ramadan. And the Hajj, that is the pilgrim to Mecca.