Final answer:
The one fixed point in establishing a chronology of Paul's life and ministry is his conversion on the road to Damascus. So, the correct answer is option a.
Step-by-step explanation:
The one fixed point in establishing a chronology of Paul's life and ministry is his conversion on the road to Damascus. According to the biblical account in Acts 9, Saul (later known as Paul) had a transformative experience where he encountered a blinding light and heard the voice of Jesus. This event marked a significant turning point in Paul's life, as he went from persecutor of Christians to a devoted follower and missionary of Jesus.
So, the correct answer is option a.