Final answer:
Biology is not typically a direct factor in creating the structure of western Sudan, unlike geography or cultural influences. Biology pertains to living organisms, whereas societal structures involve social, political, and economic factors.
Step-by-step explanation:
The structure of western Sudan is not significantly influenced by one of the options given. While geography, cultural influences, and economics are critical factors in the formation of societal structures, Biology is not typically a direct factor in the creation of political and social structures. Cultural variables include ethnicity, religion, and the legacies of colonialism and historical conflict. Environmental elements like soil, water, and climate also influence economic activities, like the reliance on oil exports in some regions of Africa. However, the discipline of Biology generally pertains to the study of living organisms and their processes rather than the complex interplay of human social, political, and economic systems that shape a country or region's structure.