Which equation should be used to calculate the speed of a wave?

Pllsss read the following passage: molten rocks deep inside earth cool and form rock a. the shifting of tectonic plates exposes these rocks. wind and water break rock a into small pieces. these pieces are carried over long distances and deposited at a certain location. more and more small pieces of rocks collect in layers one over the other over a period of several years and finally form a single rock called rock b.which statement is most likely correct? rock b may have fossils. rock a may have sediments. rock b may be formed due to intense heat and pressure. rock a may be formed due to compacting and cementing.