Some regions along the plane of the milky way appear dark because a) there are no stars in these regions. b) stars in these regions are hidden by interstellar gas. c) stars in these regions are hidden by interstellar dust grains. d) all the stars in these regions are very faint brown dwarfs. e) black holes trap the star light from these regions.

Explanation:

Some areas of the Milky Way seem dark because those are areas of the galaxy that are hidden by huge columns of interstellar dust that we cannot see through the visible range of the electromagnetic spectrum (which is the range in which our eyes see).

However, to solve this problem, astronomers use telescopes that work in the range of infrared and radio waves, to observe a little more through this intersetelar dust.

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.