How do index fossils scientists? a .they aid in the study of ranges of different organisms. b. they advance understanding of the origin of life on earth. c. they aid in comparison of rock layers at distant locations. d. they advance understanding of rock type at the time the organism lived.

D. They advance understanding of rock type at the time the organism lived.

Explanation:

Index fossils are used to identify the age of the geologic periods, it may be an animal or plant preserved in the rock strata of the Earth and characterised for a specific period of geologic time. An index fossil should be abundant in quantity and widely distributed among the geographic area in a shorter range of time. Index fossils determines the geological time scale. Index fossils may be the animals' hard body parts like teeth, bones and shells.

D. They advance understanding of rock type at the time the organism lived.

Explanation:

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