Why were west african slaves seen as desirable for the slave american

Which of the following best explains why the rhine-ruhr area became a major industrial area ?

Ihonestly don't know how to revise, like i'm struggling so much to remember things and i really don't know what to do at this rate. does anyone have any advice? especially with american history, i've got 5 topics in this section.

What did president harding's administration do to influence the american economy after world war i?