In the Parable of the Persistent Widow (Luke 18:1-8), what attribute of God does Jesus emphasize through the unjust judge?

A God's willingness to be manipulated by persistent prayer. B God's inherent disinterest in human affairs. C God's justice and the certainty that He will ultimately vindicate His elect who cry out to Him day and night. D God's approval of nagging and manipulative tactics in prayer.