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