How can tectonic plates move relative to each other ?

I know that I'm late but, the correct answer is:

The Earth's outer crust (the lithosphere) is composed of a series of tectonic plates that move on a hot flowing mantle layer called the asthenosphere. Heat within the asthenosphere creates convection currents that cause tectonic plates to move several centimeters per year relative to each other.

your answer should be c) enjoy!

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.