Rifting Sometimes Stops After an Initial Period of Faulting and Volcanism

Multiple Choice

Rifting sometimes stops after an initial period of faulting and volcanism:

A) because the asthenosphere convection current ceases.
B) but it is not known why such rifting ceases.
C) because the position of other plates stops further movement.
D) because the asthenosphere convection current is too weak to move the plates further.