Concept:Paul wrote this letter to plead for Onesimus, a runaway slave, as he returned to Philemon.
Explanation:Onesimus was a slave who had left his master Philemon.
Later, Onesimus met Paul and became a Christian.
Paul sent Onesimus back to Philemon with this personal letter.
In the letter, Paul did not order Philemon to free Onesimus or accuse Onesimus of theft.
Instead, Paul interceded for Onesimus and asked Philemon to welcome him kindly as a brother in Christ.
Thus, the main purpose was to support Onesimus during his return to his master.
Answer:A. support Onesimus as he returned to his master