Final answer:
Wood is primarily used as fuel for cooking and heating in underdeveloped countries, leading to deforestation and environmental issues due to its overexploitation.
Step-by-step explanation:
The primary use of wood in underdeveloped (poorer) countries is primarily for fuel for cooking and heating. In these regions, access to modern energy sources is often limited, making wood a critical resource for daily living. Deforestation is a significant problem in countries like Bangladesh, India, and in other tropical areas where the demand for wood, both as a fuel source and as a building material, has led to the removal of forests at rates faster than they can be replenished. As a result, many people rely on firewood for cooking, which contributes to deforestation and environmental degradation. Alternatives such as brick, cement, and cow dung for cooking have been developed, but these have not completely solved the issue of deforestation. Notably, deforestation has accelerated globally due to population growth and the increased need for agricultural land.