The correct answer is D) He restructured the city's politics and strengthened the Senate's power.
Sulla helped turn the Roman Republic into the Roman Empire in that he restructured the city's politics and strengthened the Senate's power.
We are talking about an important figure in the configuration of the Roman Republic. Sulla (138-78 BC) was a military officer and a renowned statesman that was consul two times in the Republic. He established a dictatorship in Rome by the Senate appointing him as a dictator.
