Final answer:
Saul's conversion to Christianity occurred on the road to Damascus. This significant event led to his baptism and beginning of missionary work, which helped spread Christianity throughout the Roman Empire. The correct answer is option a.
Step-by-step explanation:
Saul, later known as Paul after his conversion, experienced a transformative event on the road to Damascus as detailed in the book of Acts (9.1-2; 9.5–6) in the Christian New Testament. This event is a significant moment in Christian history as it marks the conversion of one of Christianity's most influential figures. While Saul set out to persecute Christians, he was blinded by a divine light and subsequently taken to the home of Judas on Straight Street in Damascus, where Ananias healed his blindness and baptized him. Paul's conversion contributed to the spread of Christianity throughout the Roman Empire, including cities such as Ephesus, Corinth, Thessalonica, and Rome, despite periods of persecution under Roman Emperors like Nero and Diocletian. Christianity offered a sense of hope, especially to those who were marginalized in society like slaves, and ultimately shaped the spiritual landscape of the empire, ushering in a new era of religious practice that diverged from the polytheistic beliefs that had previously dominated Roman worship.