Final answer:
The end of the Provisional Government's rule in Russia marked the beginning of the Russian Civil War, which concluded with the formation of the Soviet Union led by the Bolsheviks under Vladimir Lenin.
Step-by-step explanation:
When the Provisional Government's rule in Russia ended, a series of significant events unfolded, ultimately leading to the formation of the Soviet Union. The Russian Civil War began, which was fought between the Red Army of the Bolsheviks and various groups collectively known as the White Army. The Bolsheviks, under the leadership of Vladimir Lenin, prevailed. Consequently, the Soviet Union was formed in 1922 after the Bolshevik victory, with Lenin hailed as the leader of the new communist state.
The Russian Revolution, which had begun in February of 1917, led to the abdication of Czar Nicholas II. In the complex aftermath, which included Lenin's seizure of power and an ensuing civil war, the Bolsheviks emerged as the victors. It was only after the civil war and Lenin's efforts toward consolidating Bolshevik rule that the Soviet Union was formally established.
The correct answer to the question is B. The Soviet Union was formed.