How does the book of Philemon uniquely illustrate the transformative power of the Gospel within the context of slavery in the first century?

A It demonstrates how Christian principles could redefine relationships, challenging the social hierarchy by treating a slave (Onesimus) as a brother in Christ. B It advocates for the immediate and unconditional abolition of slavery throughout the Roman Empire. C It encourages slave owners to treat their slaves with more kindness while maintaining the existing social hierarchy. D It suggests that slaves should remain obedient to their masters until they can legally purchase their freedom.