How does the relatively short book of Philemon address the tension between Christian brotherhood and the deeply entrenched social institution of slavery in the Roman Empire?

A It explicitly condemns slavery as an inherently evil practice and calls for its immediate abolition. B It implicitly challenges the institution of slavery by appealing to Philemon to receive Onesimus, his runaway slave, as a brother in Christ. C It reinforces the social hierarchy by affirming Philemon's right to own Onesimus as property. D It ignores the issue of slavery altogether, focusing solely on personal reconciliation between Philemon and Onesimus.