Final answer:
The 5-letter term for an African tribal leader like the moro-naba of Ouagadougou is 'chief,' and the Mali Empire was established by Sundiata Keita.
Step-by-step explanation:
The 5-letter word for the leader of an African tribe, like the moro-naba of Ouagadougou, is chief. This is answer choice (a) according to the options provided. Notably, the term 'chief' is often used to denote the leader of a tribe or a community within various cultures around the world, including several African societies.
As for the creation of the empire of Mali, it was established by Sundiata Keita, who fits the description of answer choice (b). Sundiata Keita, also known as Sundiata Kieta, was a prominent ruler who laid the foundations for the Mali Empire in the 13th century and is often credited with its creation.