Concept:Rapid urban population growth in developing African countries is caused mainly by rural-to-urban migration.Explanation:People leave rural areas and move to cities in large numbers.Their main goal is to find jobs and improve their economic condition.Medical facilities, living space, and security may also attract people, but these are not the primary cause.The strongest reason for this rapid movement is the search for employment opportunities.Answer:B. Many people migrate to urban areas in search of jobs