Answer:
D: He restructured the city's politics and strengthened the Senate's power.
Step-by-step explanation:
In the Constitutional reforms enacted between 82 and 80 BC, Sulla decreed strengthening of the Roman Senate, reducing the power of the plebeian tribunes and democracy in Rome. Along with the fact that he was appointed the dictator, this was the beginning of the end of the Roman Republic and the event that foreshadowed the civil war and the becoming of the Roman empire.