The correct option is B Richard Burton, John Speke
Europeans had never explored the interiors of Africa thoroughly. But, gradually, the Europeans started sending explorers to the interiors, to make maps for others to follow. In the 1850s and 1860s, Richard Burton, John Speke, and James Grant traced lakes and rivers and found the source of the river Nile. By the end of the 19th century, the Europeans had learnt about more African rivers like the Zambezi, Niger and Congo. Therefore by exploring the interiors of Africa, the Europeans could map out the distribution of natural resources in Africa.