In the Parable of the Persistent Widow (Luke 18:1-8), what key theological principle is Jesus emphasizing through the contrast between the unjust judge and God?

A That God is similar to the unjust judge and requires relentless pleading. B The importance of public displays of piety to influence divine favor. C God's character as a just and responsive God who answers prayer, even when delayed. D That God is indifferent to human suffering and only intervenes sporadically.