The Source of Jesus' Authority

We have come in Mark's Gospel to the last week of Jesus' life. Starting with the present text, Jesus will now begin a series of encounters with the Jewish authorities, which will culminate in his arrest and execution. In this first encounter, the Jewish authorities confront Jesus about his actions on the previous day, when he protested in the temple. Their challenge is a question about what authority he has to give command concerning what happens in the temple.
Jesus counters with a question of his own, and at first it may seem unconnected to the present scene. Jesus demands of them where the baptism of John the baptist was from, whether heaven or men.
What Jesus is asking here is whether John's ministry was authorized by God or whether John took his own initiative, apart from God's will and direction, to start baptizing people. The point of this question is simply this: Was John a genuine, God-sent prophet or was he something less, perhaps even a fake?