The African plate is stationary and that it has not moved during ______ years.

A．the structure of the African plates
B．the revival of dead volcanoes
C．the mobility of the continents.
D．the formation of new oceans

A．the features of volcanic activities
B．the importance of the theory about drifting plates
C．the significance of hot spots in geophysical studies
D．the process of the formation of volcanoes