Concept:Population density in Nigeria is determined by factors that either attract settlement or make an area unsuitable for living and farming.
Explanation:Tsetse fly infestation limits population because it spreads sleeping sickness and prevents keeping livestock.
Fertile agricultural land is a major pull factor; it draws people to settle and farm in areas with good crop yields.
Thick forest vegetation is difficult to clear, so it discourages farming and permanent settlement, thus lowering population density.
Mining does attract workers to towns like Jos and Enugu, but this effect is localized and limited to a few parts of the country.
Its influence on the national pattern of population distribution is significantly smaller than that of the other three factors.
Therefore, mining least influences population density in Nigeria overall.
Answer:B. Mining.