Final answer:
The correct answer is option d) Kirov was an influential figure in Leningrad.
Step-by-step explanation:
Sergei Kirov's political positioning posed a significant threat to Joseph Stalin for several reasons. Kirov advocated for a more liberal regime, which contrasted sharply with Stalin's authoritative and repressive tactics. Additionally, Kirov was an influential figure in Leningrad, garnering wide support from the party members in that region, challenging Stalin's dominance over the Soviet Union's political landscape.
The context of the political rivalry is rooted in the turmoil following Lenin's death and Stalin's rise to power. Stalin sought to consolidate control over the Communist Party and was suspicious of other high-ranking officials. Kirov's popularity and his contrasting ideology represented a direct challenge to Stalin's authority, ultimately leading to Kirov's assassination, an event that fueled Stalin's Great Purge.