Why are index fossils useful for determining the age of other fossils or rock layers?

What is earths lithospheric plates interact at

Which best describes a rhinovirus? o a. a virus that causes a common cold o b. a protective shell around a virus o c. a tube the comes off a virus o d. a piece of dna transferred by a virus

The similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between organisms in both locations?