Final answer:
Joseph testified to Potiphar that God was with him and made everything he did prosperous. This biblical narrative dates around 1800 BCE when Joseph was in Egypt.
Step-by-step explanation:
The correct answer to the student's question is that Joseph's testimony to Potiphar was that God was with him and made all he did prosperous. According to the biblical account around 1800 BCE in the book of Genesis, Joseph, who was sold into slavery in Egypt, found favor with Potiphar because the Lord was with him. Everything Joseph did was successful because of the Lord's presence. This eventually led to Joseph gaining great responsibility and authority in Potiphar's household.