Lithospheric plates move apart under the ocean floor.
Explanation:
The mantel convection currents movement occurs it stretches the crust apart. The heat from convection currents makes the the Earth crust molecules less stable because the heat makes them move apart and shake on molecular level which makes crust more flexible.
It would protect best against C) Alpha radiation, as Beta radiation is stopped by lighter metals such as aluminium, and Gamma radiation can only be stopped by heavier metals such as lead.
