Which posed the greatest challenge to pioneers crossing the western mountains? a: american indian attacks
b: lack of water
c: hot desert sand
d: dangerous passes

on november 6 and 7, 1917 (or october 24 and 25 on the julian calendar, which is why the event is often referred to as the october revolution), leftist revolutionaries led by bolshevik party leader vladimir lenin launched a nearly bloodless coup d'état against the duma's provisional government.