How does the book of Philemon address the social issue of slavery in the first century, and what principle does Paul emphasize in his appeal on behalf of Onesimus?

A Paul explicitly condemns slavery and demands Philemon's immediate compliance with Roman law. B Paul ignores the issue of slavery, focusing solely on Onesimus's spiritual transformation. C Paul advocates for violent rebellion against slave owners to establish social justice. D Paul appeals to Philemon to receive Onesimus back not as a slave, but as a beloved brother in Christ, emphasizing reconciliation and equality within the Christian community.