Shifts in the Earth's crust cause tectonic plates to shift along the fault lines. This causes extreme friction & energy which is released in waves, causing an earthquake.
I'd say B and D definitely, and also E but I'm not entirely sure about that
Africa has 54 different countries
Oceanography is the study of the ocean and the cryosphere are the portions of the earth that are just frozen water (ice). When fresh water glaciers melt, they lower the salt levels in the ocean and and oceanographer studies that and makes sure that it wont have too much of an effect. The cryosphere plays a significant role in the global climate.