How can brain drain affect home countries?

The great scientist alfred wegener proposed that continents have moved, while other scientists such as t. c.chamberlin argued against wegener. wegener's ideas eventually won, and are now widely accepted, because: a) wegener's ideas were more beautiful, and so were favored by the intellectual elite. b) wegener's ideas did a better job of predicting the results of new observations and experiments. c) wegener's ideas appealed to dead white european males, whereas chamberlin's didn't. d) wegener's ideas appalled dead white european males, and we all know that in this politically correct era, dead white european males cannot get a fair shake. e) wegener won the nobel prize.

In 2002, north korea announced that it was shutting down its nuclear facilities constructing a hydroelectric energy plant restarting nuclear weapon development changing to a free market economy

One disadvantage that darwin faces today is w. enemy attacks x. natural disasters y. lack of land bridge z. high population density