Answer: Correct Answer: Lateran Treaty

Pope Pius XI played a pivotal role in shaping the modern identity of the papacy through the signing of the Lateran Treaty in 1929. This landmark agreement between the Holy See and the Kingdom of Italy, negotiated with Benito Mussolini, resolved the longstanding "Roman Question" that had lingered since the fall of the Papal States in 1870. The treaty recognized Vatican City as an independent sovereign entity, granted the Church financial compensation, and affirmed Catholicism as Italy’s state religion. Pius XI’s diplomatic acumen not only restored the papacy’s temporal footing but also redefined its spiritual and political influence in the 20th century.