The correct answer is Wegener's theory did not explain how the continents could move.
The theory given by Wegener's states that once the continents were once joined together but the continents are separated now. He was not able to tell the name of the force that made the continents apart. He did not have any explanation regarding the fact or the reason behind continental drift. The theory of plate tectonics on the other hand describes that the continents were broken down into slabs which moves as a result of movement of tectonic plates.
