Answer:
[tex]\boxed {\tt Tectonic \ plates}[/tex]
Explanation:
We want to find the choice for something that is in constant motion and changes the forms of the Earth's crust.
Solar flares, lunar phases, and magnetic fields do not affect the Earth's crust as much as tectonic plates.
Tectonic plactes are always moving and changing pieces of the Earth's crust. They float on top of the mantle and collide with each other, causing earthquakes, volcanoes, and more.
The best answer choice is B. Tectonic plates
