What characterizes the transform theory?

The transform theory describes the movements of tectonic plates where they slide past one another horizontally. This movement occurs along transform or strike-slip faults, which are fractures in the Earth's crust where two blocks of land slide past each other.

In this context, the main characteristic of transform boundaries is that they do not involve the creation or destruction of crust, as is the case with divergent or convergent boundaries. Instead, as the plates move side by side, stress is accumulated until it is released in the form of an earthquake. This lateral movement is essential to understanding how seismic activity occurs, as the friction between the plates can lead to significant geological events when the accumulated stress is finally released.

The other options involve different types of plate movements not associated with the transform theory. For instance, moving apart refers to divergent boundaries where new crust is created, and colliding refers to convergent boundaries where one plate moves under another. Vertical movements are also not characteristic of transform boundaries, which are exclusively lateral. Therefore, the correct answer accurately reflects the distinctive nature of transform plate interactions.