Correct Option: A. Peter's Detailed Explanation: The event referred to in the question is the Day of Pentecost, which is described in the Book of Acts in the New Testament of the Bible, specifically Acts 2. This day is significant in Christian history as it marks the descent of the Holy Spirit upon the apostles and the beginning of the Christian Church.

1. Context of the Event:
2. After the resurrection of Jesus, He instructed His disciples to wait in Jerusalem for the Holy Spirit. On the Day of Pentecost, which occurred fifty days after Easter, the Holy Spirit descended upon the apostles, enabling them to speak in various languages.
3. This miraculous event attracted a large crowd of Jews from different nations who were in Jerusalem for the festival.
4. Peter's Address:
5. Peter, one of Jesus' closest disciples, stood up among the apostles and addressed the crowd. His speech is recorded in Acts 2:14-41.
6. In his address, Peter explained the significance of the events that had just occurred, citing the prophecy of Joel and affirming that Jesus was the Messiah who had been crucified and resurrected.
7. He called the people to repentance and baptism in the name of Jesus Christ for the forgiveness of their sins.
8. Conversion of Three Thousand Souls:
9. The impact of Peter's address was profound. According to Acts 2:41, about three thousand people accepted his message and were baptized that day, marking a significant moment in the growth of the early Church.

Why the Other Options are Wrong or Weaker:

• B. James:
• James, the brother of Jesus, was a prominent leader in the early Church, but he did not deliver the address on the Day of Pentecost. His role became more prominent later in the Jerusalem Church, particularly in Acts 15 during the Council of Jerusalem.
• C. Paul:
• Paul, originally known as Saul, was not a follower of Jesus during His earthly ministry and was not present at Pentecost. His conversion occurred later, after the events of Pentecost, when he encountered the risen Christ on the road to Damascus (Acts 9).
• D. John:
• John, another of Jesus' disciples, was present at Pentecost but did not deliver the sermon that led to the conversion of three thousand souls. His contributions to the early Church are significant, but he is not the one associated with this particular event.

Revision Summary:

• The conversion of three thousand souls on Pentecost was due to Peter's address.
• Peter explained the significance of the Holy Spirit's descent and called for repentance.
• The event is recorded in Acts 2, highlighting the birth of the Christian Church.
• Other apostles like James, Paul, and John played important roles but were not responsible for this specific conversion event.