The elders at Jerusalem advised Paul on his arrival in the city to

The question is asking about what advice Paul was given by the elders in Jerusalem when he arrived in the city. The options are A. avoid the Jewish Christians, B. purify himself along with men under vows, C. join those in the temple for prayer and fasting, and D. preach the good news.

The correct answer is B. Paul was advised to purify himself along with men under vows. This means that he was to undergo a ritual purification process in order to be considered pure and acceptable to God. The men under vows were likely those who had taken a Nazarite vow and were required to undergo this purification process.

It is important to note that this advice was specific to Paul's situation at the time and may not apply to all Christians in all circumstances. Additionally, the advice given by the elders was not the same as a commandment from God, but rather a suggestion based on their understanding of Jewish customs and traditions.

Overall, this question is testing your knowledge of the events in the book of Acts and your understanding of the cultural context in which they occurred. To learn more about this, please read the relevant sections of the recommended textbooks.