Concept:Under-development in West Africa is linked to factors that slow economic growth, such as rapid population growth without matching resources.Explanation:Availability of manpower, high capital formation, and large market size are generally positive conditions for development, not causes of under-development.Rapidly increasing population can cause under-development when it outpaces food supply, jobs, and infrastructure.This leads to low income per head, poverty, and pressure on public services.Answer:B. increasing population