How does the Apostle Paul's appeal to Philemon regarding Onesimus challenge the social norms and legal practices of the Roman Empire concerning slavery?

A Paul explicitly condemns slavery as an inherently evil institution, demanding Philemon's immediate manumission of Onesimus. B Paul strategically uses Roman law to force Philemon to free Onesimus by highlighting Onesimus's potential citizenship. C Paul subtly navigates the complex social hierarchy by appealing to Philemon's Christian values, urging him to receive Onesimus not as a slave, but as a beloved brother, thereby undermining the master-slave dynamic within the Christian community. D Paul ignores the issue of slavery entirely, focusing solely on Onesimus's spiritual transformation and reintegration into the Colossian church.