What is the meaning of the prefix sub-in submarine please help it's an exam

Africa, 1914 which statement is the best conclusion for the information presented in the map? a) european colonization had a positive impact on african nations. b) african colonization the economic growth of all european nations involved. c) by the outbreak of world war i, most of the african continent was under english control. d) by the outbreak of world war i, most of the african continent was under european control.