Final answer:
Coastal societies likely benefited the most due to trade opportunities, while inland communities benefited the least due to isolation.
Step-by-step explanation:
The African groups that likely benefited most from the spread of new belief systems during the Middle Ages were the coastal societies because of the trade opportunities that came with the adoption of these belief systems. Coastal societies had access to important trade routes and established connections with merchants from other regions, allowing them to enhance their economic and cultural prosperity.
On the other hand, the inland communities benefited least as they faced geographic isolation. They were situated further away from major trade routes and lacked easy access to external influences, making it challenging for them to benefit from the spread of new belief systems and the opportunities they brought.