In the Parable of the Persistent Widow (Luke 18:1-8), what is the primary lesson Jesus intends to convey about prayer, considering the unjust judge's eventual response?

A God is like the unjust judge and will eventually grant requests to avoid annoyance. B Only prayers offered frequently and persistently will be answered. C The importance of unwavering faith and perseverance in prayer, even when answers seem delayed or impossible. D God only responds to prayers from those who are socially marginalized and oppressed.