The correct options are
B The coastline of Africa does not have bays and inlets that cut into it.
C The continent of Africa can be considered a vast plateau made of ancient crystalline rocks.
D The African plateau is higher in the southeast and slopes gently towards the northeast.
The whole continent of Africa can be considered a vast plateau made of ancient crystalline rocks. It rises steeply from a narrow coastal fringe. The plateau is higher in the southeast and slopes towards the northeast. The coast line of Africa is almost straight and it includes a few large basins, estuaries and natural harbours. In comparison to other continents, considering its size, Africa has fewer mountains and lowlands.