Considering the parable of the Persistent Widow (Luke 18:1-8), what is the primary theological lesson Jesus intended to convey through this story?

A God will always grant immediate justice to those who suffer. B Prayer should be offered only in times of great need. C Persistent prayer demonstrates a lack of faith in God's timing. D Consistent and unwavering prayer, even when unanswered, is essential because God will ultimately bring justice.