A decade ago places like Ivory Coast and Equatorial Guinea were being largely ignored by the petroleum world majors for the following are reasons EXCEPT that ______.
A．the majors preferred the large oil sources like Negeria and Angola
B．the drilling sites of the large sources could be leased at a relatively low price
C．the petroleum potential of Ivory Coast and Equatorial Guinea has yet to be proved
D．the majors could not find the states in their oil map