In the Parable of the Persistent Widow (Luke 18:1-8), what is the primary theological lesson regarding prayer that Jesus intends to convey?

A God only answers the prayers of the most righteous individuals. B God is ultimately unjust and requires constant nagging to act on behalf of his people. C Persistent and unwavering prayer, even in the face of apparent indifference, is essential for receiving God's justice and provision. D Prayer is primarily a performative act intended to impress others with one's piety.