How does the Apostle Paul's appeal to Philemon regarding Onesimus challenge the social norms and legal structures of the Roman Empire in the 1st century?

A Paul explicitly condemns the institution of slavery and demands its immediate abolition throughout the empire. B Paul seeks to subtly undermine the existing power structures by appealing to Philemon's Christian values and urging him to receive Onesimus not as a slave, but as a brother in Christ. C Paul primarily focuses on the economic benefits of freeing Onesimus, arguing that it will boost Philemon's business. D Paul threatens Philemon with excommunication from the Christian community if he does not comply with his demands.