What does Mark 11:27 mean?

Since Jesus and the disciples reached the area around Jerusalem, they have spent nights on the Mount of Olives, east of the Temple Mount (Luke 21:37–38). Their friends Mary, Martha, and Lazarus live on the southeastern slope, in Bethany. From Bethany, it is a short walk northwest to Bethphage, and about as far down the mountain, across the Kidron Valley, and up to the East Gate of the temple. In fact, the most direct route from the east to Jerusalem is through the temple courtyard.

The three groups mentioned are all leaders in Jerusalem. The chief priests are descended from Moses' brother Aaron. At this time, they consist of former high priests and those priests who serve in the temple regularly.

Scribes are experts in the Mosaic law. It was the scribes who came up with the "Oral Law." They felt the written law of Moses was too vague in some areas, such as exactly what constitutes "work" on the Sabbath. To ensure nobody broke the written laws, the scribes derived additional regulations and claimed God gave these to Moses on Mt. Sinai, but that Moses didn't write them down. Their manmade traditions had the opposite effect they'd intended: the extra rules often nullify the actual intent of the laws as given by (Mark 7:13).

We're not told exactly who the elders are. Generally, they are adult men who help make decisions in a local community. They may be patriarchs of significant families (Exodus 3:16) or specially chosen judges (Exodus 24). Ezra and Nehemiah were elders who led the Jews in returning to Israel from Babylon. Most likely, the elders who confront Jesus are the wealthy aristocracy of Jerusalem.