Which of the Following Statements Concerning the Portuguese Presence in East

Which of the following statements concerning the Portuguese presence in east Africa is most accurate?

A) After the 1570s, the Portuguese gained complete control over the east African trade in the Indian Ocean and the Red Sea.
B) Unlike the Portuguese settlements on the coast of western Africa, Mozambique became the basis for a large European colony.
C) Portuguese bases on Mozambique, Mombassa, Sofala, and Kilwa gave them access to the gold trade of east Africa, but they were unable to completely disrupt the Muslim trade with the region.
D) The Portuguese presence in east Africa precipitated the population movement among the Bantu that became the Mfecane.