Step 1: Recall succession crisis.
After Lenin’s death in 1924, there was a power struggle between Joseph Stalin and Leon Trotsky.
Step 2: Outcome.
Stalin eventually consolidated power, became the General Secretary, and ruled USSR for decades.
Step 3: Eliminate options.
(A) Mazzini: Italian leader, unrelated.
(C) Trotsky: Strong rival but lost to Stalin.
(D) Kerensky: Leader before Bolsheviks, not Lenin’s successor.
Step 4: Conclusion.
Correct answer: (B) Stalin.