The answer please answer will give brainliest

Which plains area lies in both the united states and canada? altiplano central canadian shield coastal plains great plains

The observations of hooke and van leeuwenhoek documenting the existence of microscopic cells formed the basis of what important theory? a. the cell theory stating that all living things are composed of cellsb. the theory of spontaneous generation, which held that life forms could arise spontaneouslyc. the theory of chemotherapy, or use of antimicrobials to destroy pathogenic organismsd. the germ theory of disease and causative agents

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time