Portuguese Mariners Initially Sailed Up the Congo River in the 1480s

Portuguese mariners initially sailed up the Congo River in the 1480s in hopes of:

A) Finding a passage to the Indies across Africa.
B) Conquering the land of Mozambique on the East African coast.
C) Linking up with Prester John, who could help with the conquest of Jerusalem.
D) Converting the powerful King of Kongo to Christianity.