What does earth magnetic field protect us from?

Why are fossils of organism's from the phanerozoic eon much more likely to be found than fossils of organisms from any other eon? a. more organisms present during the phanerozoic eon had soft body parts. b. organisms present during the phanerozoic eon were all microscopic. c. more organisms present during the phanerozoic eon had hard body parts. d. organisms present during the phanerozoic eon are the most ancient life forms.

The hebrews originally migrated from a. india b. egypt c. arabia d. mesopotamia

What tests were able to determine when continental crust was formed?