The statement that best analyzes the challenges Lenin faced in making Russia into the USSR is: "While Marx had argued that the communist revolution would occur from factory workers, Russia was primarily an empire of farmers."
This response highlights a fundamental issue that Lenin encountered: the discrepancy between Marxist theory, which anticipated revolution emerging from industrialized societies with a strong working class, and the reality of Russia, which was predominantly agrarian. This demographic challenge significantly impacted Lenin's ability to implement communist principles effectively.