Mark 11:31-33 - We don't know

11:31,32

The religious leaders were afraid to answer. If they say John’s authority came from heaven, then they would have to explain why they didn’t believe John. And since John pointed the way to Jesus, why didn’t they believe Jesus now? Conversely, if they said John had merely human authority, i.e. effectively had no authority at all, then the crowds would be against them. This refusal to believe John or Jesus was not a matter of intellectual unbelief, but rebellion against God. This rebellion is the root of anyone’s refusal to believe Jesus. This does not mean we should never use apologetic type arguments, but we do need to recognise the underlying problem of all mankind.

11:33

So they reply “We do not know”. Given that they were the religious leaders, this is a rather humiliating response. They were the religious experts, they should be able to answer. However, those with apparent authority are not always as powerful as they make themselves out to be. Since they refused to answer His question,  Jesus declined to answer their question.