Which sphere extends from earth’s core to earth’s crust

After considering options, a student using the problem-solving process should next

Which of the following can scientists estimate geologic time? a.observing rock sequences b.radiometric dating c.comparing fossils d.all of these

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted