Question

answer the questions about the diagram. organism a appears in the least outcrops. organisms are the oldest. make the best index fossil. organism a and b, organism b and c, organism c and d, organism d and a

Explanation:

Index fossils are from short - lived organisms widespread geographically. Organisms A and B appear in the least outcrops, suggesting they may be good index fossils as they can help date rock layers more precisely compared to more widespread ones.

Answer:

A. Organism A and B