Question

a scientist finds a fossil that she thinks might make a good index fossil. which characteristic does this fossil most likely have? it is the remains of an organism still found alive today it is the remains of an organism that is found in abundance nearby it is the only fossil for this type of organism that has ever been found it is the remains of an organism that lived in a narrow geographic area.

Explanation:

Index fossils are fossils that are used to define and identify geologic periods. They are typically the remains of organisms that were abundant, widespread, and existed for a relatively short period of time. An organism that is found in abundance nearby (and likely was widespread in its time) is more likely to be an index fossil. An organism still alive today cannot be an index fossil (as index fossils are from specific past geological periods). If it is the only fossil of its type ever found, it cannot be used widely to correlate rock layers (a key function of index fossils). An organism that lived in a narrow geographic area would not be useful for widespread correlation of rock layers (another key function of index fossils).

Answer:

It is the remains of an organism that is found in abundance nearby.