In the Parable of the Persistent Widow (Luke 18:1-8), what is the primary point Jesus is making about prayer, beyond simply encouraging perseverance?

A God is unjust and needs to be worn down by constant requests before answering. B Prayer should only be directed to authority figures who can grant our requests. C God, unlike the unjust judge, is inherently just and will answer the cries of those who persistently seek justice, even when it seems delayed. D Prayer is only effective when performed publicly and repeatedly.