Which of the following areas in Tropical Africa is densely populated?

Step 1: Analyze the question The question asks which area in Tropical Africa has a high population density. In Geography, density depends on climate, soil fertility, urbanization, economic activity and history.

Step 2: Concept: factors that affect population density

• Favourable factors: reliable rainfall, fertile soils, urban and industrial centres, trade, and good transport.
• Unfavourable factors: aridity, poor soils, tsetse fly and disease, swampy or difficult terrain, and sparse economic opportunities.

Step 3: Evaluate each option

• A. South-western Nigeria: This area has reliable rainfall, fertile soils for cocoa and food crops, and a long history of urbanization. It has big cities such as Lagos, Ibadan, Abeokuta and Ogbomoso, and Lagos is one of the most densely populated places in Africa. It is densely populated.
• B. The middle belt of West Africa: This area is generally sparsely populated. Its historical problems include the tsetse fly, the slave-raid legacy and poor development, so it has low density.
• C. The Sahel region: This area has low and unreliable rainfall, desertification and poor vegetation, so it is thinly populated.
• D. The Niger Delta: It is true that some parts, such as Port Harcourt, are crowded. But the Delta as a whole is swampy, flood-prone and hard to settle, so its settlements are scattered and its overall density is lower than that of the south-west.

Step 4: Answer South-western Nigeria is the best choice, so the answer is A.

Tip: For "densely populated" questions, look for reliable rainfall + fertile soil + big cities. For "sparsely populated" questions, look for desert, swamp, tsetse fly or rugged terrain.