How Did Stalin's Approach to Consolidating Power Differ from Lenin's

How did Stalin's approach to consolidating power differ from Lenin's?

A) Lenin was generally far more brutal to both enemies and allies within the party than Stalin.
B) Lenin rarely expelled party members, whereas Stalin often expelled members.
C) Lenin set rival parties against each other, whereas Stalin set rivals within the party against each other.
D) Stalin allowed rival parties to form and operate, whereas Lenin made rival parties illegal.
E) Stalin built up multiple other leaders within the party so they could take over later, whereas Lenin focused all authority on himself.