Can someone help me with this question please?

Which statement summarizes the theory of plate tectonics?

A.
Only the continents move, traveling slowly over and through Earth’s crust.

B.
All of the continents were once joined together into a single supercontinent.

C.
The continents are fixed and have always been located in their present positions.

D.
Earth’s crust is made of pieces that move slowly over, against, and apart from each other.