what evidence have you discovered to explain how the fossil record provides relative ages? use the words: mass extinction, superposition, fossils, and relative age

Relative dating is based on the positions of fossils in rock layers. Lower layers were laid down earlier, so they are assumed to contain older fossils. This gives the fossil an approximate age in years. Absolute dating is often based on the amount of carbon-14 or other radioactive element that remains in a fossil up until extinction.

it's c. elements are placed in rows based on how may valencies electrons have.