What Is the Purpose of Fencing in a High Availability

What is the purpose of fencing in a high availability cluster?

A) Prevent failed nodes from interfering with the remaining intact part of the cluster.
B) Ensure a consistent assignment of all network connections from a client to the same cluster server.
C) Define constraints on which services may run on the same cluster node.
D) Enforce storage quota and other resource limitations for each service provided by the cluster.
E) Provide multi-tenancy cluster configuration for cloud computing.