Within the Parable of the Persistent Widow (Luke 18:1-8), what primary theological truth about prayer does Jesus intend to illustrate?

A God is reluctant to answer prayers and needs to be continually pestered. B God will only answer prayers offered by the most righteous individuals. C Consistent and unwavering prayer, even in the face of apparent unanswered pleas, demonstrates faith and aligns with God's will. D The parable teaches that if we pray long enough, God is obligated to grant our requests, regardless of their nature.