What mountain ranges make up part of the alpine mountain system?

Gold is not now being extracted from seawater. why not? a. it would be too disruptive to marine life to develop any marine mineral resources b. there is no gold in seawater c. we don't know how to extract minerals from seawater d. it would be too costly and difficult to separate the small amount of gold from the very large amounts of halite and other minerals

Which of the following statements best explains why there tends to be a greater number of large cities in southern africa than the east africa

Can someone me with this plz? ! i'm putting 20 points on it!