Question

what is the primary purpose of organizing fossils into a fossil record?
to find the precise radioactive age of every fossil discovered
to prove that the oldest rock layers are always at the bottom
to collect as many different types of rocks as possible
to document the history of life and how it has changed over time

Explanation:

The fossil record is a chronological collection of fossils that helps scientists understand the history of life on Earth, including the evolution and changes in species over time. It is not mainly about finding radioactive ages of every fossil, proving rock - layer positions, or collecting rock types.

Answer:

To document the history of life and how it has changed over time