Mass is expressed in what type of units

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

Which of the following terms best matches this definition: the process where humans choose the traits that will be present in the next generation through breeding. question 4 options: genetic determinism artificial selection acquired selection natural selection