Which of the following was a common life form during the Cambrian Period? A. trilobite B. bryozoan C. land plant D. cephalopod

Which element is used in photosynthesis found in atmosphere and fixed by bacteria?

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

Amap's orientation is typically determined by an