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 challenge for Lenin, as the basis of Marxist theory relied on a proletarian revolution led by industrial workers, while Russia's population was largely agrarian. This disconnect between Marxist theory and the actual conditions in Russia created significant obstacles for Lenin in implementing a communist regime.