Explain briefly the difference between spot height and trigonometrical points​

A spot height shows exact heights by a black dot with a number next to it. The number is the height above sea level in metres. Trig points or Triangulation Pillars are another way of spotting the top of a mountain on a map. ... The number beside it shows the height above sea level.

are there any options you can choose from? ?

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.