I think 3rd choice is the correct answer
Vladimir Lenin was a Russian communist leader who led the Bolshevick Revolution, Stalin took over after continuing to rule by fear.
A population cencus is an official count of the population.
Some pros and cons of European exploration of America include the following:
Pros:
European settlement helped to develop North American cultures technologically
European exploration increased global understanding of the world's actual geography
Cons:
European exploration spread diseases
North American cultures were largely rejected and Natives were often treated as savages
Hope this helps!