why was it critical for good pioneer trails going west to have a decent route through the Rocky mountains

The holocaust of world war ii resulted in a) the nazis effectively used propaganda to gain and hold power in germany. b) ethnic regimes carried out mass devastation. c) deporting all european jews to the island of madagascar. d) the systematic mass slaughter of european jews and and others in nazi concentration camps during world war ii.

Brainliesttt !me : ) what brought about the end of the soviet union?

List five north american and european countries in the non-communist bloc