Which of the following are examples of the diffusion of Islam?

I. Muslim merchants spread Islam to African traders on the trans-Saharan route.
II. Medieval Spanish architecture incorporates Islamic art.
III. Ottoman Turks converted the Hagia Sophia into a mosque.
IV. Muslim artists do not include human figures in their religious art.

Answer Choices:
1. I only
2. III and IV
3. I, II and III
4. I, III and IV
5. II, III, and IV