in the documentary mr. smith goes to washington, mr. smith decides to speak for hours on the senate floor. what is this called?

What was one of the most important causes of the russian revolution of 1917? a. the german occupation of russia during world war ii b. the bolsheviks execution of czar nicholas ii and his family c. csar nicholas ii refusal to withdraw from world war 1 d. the policy of ethnic discrimination put in place by the duma