Because the Climate of a Region Slowly Changes and Tectonic

Because the climate of a region slowly changes and tectonic adjustments slowly occur,the landscape

A) is continuously adjusting,and in a state of dynamic equilibrium,but not constantly at a threshold.
B) is usually in a state of dynamic equilibrium.
C) is constantly at a threshold condition.
D) is constantly at a threshold,continuously adjusting,and in a state of dynamic equilibrium,.
E) is continuously adjusting to new conditions that develop.