Most saltwater-use is to
irrigate crops
provide the public with drinking water
manufacture products like tires and cars
generate electricity

Most saltwater-use is to generate electricity. Since salt water naturally has electrolytes that can sustain in generating an electricity. This is also the reason why it is not advisable for people to swim in the ocean when it’s raining or there is a thunderstorm or visible lightning.

since there isn't any suggested answers i will give you the reason and hopefully you can figure it

south africa, or rather all of africa, has not been in the location in which it is nowadays throughout the geological past. after the super-continent pangaea started to break apart, gondwanaland, in which was africa, moved further south, and parts of it came to be very close to the south pole. because the climate in this part of the world is very cold due to the very dispersed sun rays in there, what is now south africa, started to freeze, and the conditions were right for the formation of glaciers. the glaciers existed up until the period when gondwanaland started to break apart and what is now africa started to move towards north, sp it warmed up and the glaciers melted.