The correct answer is D) extended lineages.
The core social factor that gave people a sense of community and shared responsibility in medieval African culture was extended lineages.
During the Medieval times in Africa, one of the cultures that flourished was the Sao culture, which inhabited the territories of Central Africa, close to the Chad River. This tribe developed knowledge in the work of tools using bronze, and iron. Another important culture in Medieval times was the Kanem civilization, which inhabited territories of Nigeria, Lybia, and Chad. The Shilluk Kingdom and the Luba kingdom were other important cultures of the time, in which the core social factor that gave people a sense of community and shared responsibility was extended lineages.