Final answer:
The Sahara and Sahel zones were pivotal in facilitating trade routes that enabled cultural exchange and the widespread distribution of products, as well as the diffusion of cultural influences, particularly the spread of Islam, between East and West Africa.
Step-by-step explanation:
The Sahara and Sahel zones influenced cultural exchange between East and West Africa primarily by facilitating trade routes and the exchange of goods, which corresponds to option A. These regions were crucial in connecting diverse peoples, allowing for the movement of commodities as well as cultural and religious exchanges.
Trans-Saharan trade routes effectively united markets and products across distant lands, forming an intricate network spanning from West Africa to the Middle East and Europe. Trading centers like Awdaghost and Djenné became hubs of commerce and culture, spreading influences such as Islam and facilitating the adoption of shared values, laws, and languages.
The spread of Islam played a significant role in unifying regional trade into a cross-desert system of commerce, due to the shared set of customs, laws, traditions, and language provided by Islamic tradition. This religious unity further reinforced trust among Muslim traders, which, alongside the development afforded by Arab literacy, boosted the trans-Saharan trade. Religious syncretism also emerged as local elites began to integrate Islam with traditional beliefs, further enriching cultural exchange.