Question

select the qualities of an index fossil *
lived for a very long time in geologic terms
lived for a relatively short time in geologic terms
is limited to specific areas is therefore more likely to provide accurate dating of rock layers
is found in a widespread geographic area. it can then be used to date sedimentary layers over very long distances.
found in high numbers. this makes them more likely to be found
found in low numbers. this allows specific dating of a particular time period
easily recognizable

Explanation:

Index fossils are used to date rock layers. They need to be in high numbers (more likely to be found), have a short geological lifespan (so the rock layer they're in is from a specific time), be widespread (for dating over large areas), and easily recognizable.

Answer:

• Lived for a relatively short time in geologic terms
• Is found in a widespread geographic area. It can then be used to date sedimentary layers over very long distances
• Found in high numbers. this makes them more likely to be found
• Easily recognizable