What events brought on the second red scare?

Following archduke franz ferdinand's assassination, austro-hungarian leaders: a. aided the ottoman empire in its campaign to keep serbia under its control. b. executed nearly all prominent serbs living in austria-hungary c. threatened to invade serbia if serb leaders did not agree to a set of strict demands. d.. formed an alliance with great britain to protect austria-hungary from future attacks.

Was the amassing of men, equipment, and supplies for the 1944 invasion of europe. operation varsity operation nordwind operation dragoon operation overload operation torch

What from the columbian exchange had perhaps the biggest impact on the world?