How is relative-age dating used to determine the ages of fossils?

a. by observing the formation of sedimentary rocks

b. by using radioactive isotopes

c. by estimating the number of fossils in a particular region

d. by the formation of igneous rocks e. by identifying the way the fossils were formed

A. by observing the formation of sedimentary rocks

Explanation:

Relative age dating does not tell us how many millions of years the rock is. It informs us that this rock is older or younger than another or if it was formed before or after a certain geological event. This is done by observing the formation of sedimentary rocks.

Relative age dating is widely used in geology and manages to bring us a lot of information about the planet's past and the formation of sediments and soil in general.