Select the tools and tactics used by leaders like hitler, mussolini, and stalin during the years of their build-up to power: a. propaganda b. open international diplomacy c. oratory skills d. secret police e. international trade f. all of these were used

A, C and D--propaganda, oratory skills, and secret police.

Totalitarian leaders convince their people through speeches there is something wrong or to fear and then use propaganda to demonstrate "evidence" of the group that is to fear or be punished. Secret police were used to consolidate the power of the leader as well as silence those that spoke out against the leadership. 

Total obedience was necessary to secure the power of totalitarian regimes like those of Stalin, Hitler, and Mussolini. They all created large military and increased industrial production to make their countries more self-sufficient.