What is the theological importance of Onesimus's transformation, as depicted in Paul's letter to Philemon?

A It demonstrated Paul's power to forgive sins and grant salvation. B It illustrated the early church's acceptance of slavery as a legitimate social institution. C It exemplified the potential for reconciliation and brotherhood in Christ, transcending social and legal barriers (Philemon 1:16). D It highlighted the importance of obedience to earthly masters regardless of their behavior.