Determining a common ancestor between two species provides information about A.
the evolutionary past
B.
relatedness
C.
rate of reproduction
D.
Both A and B

the answer to your question is tooth decay.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.