Which Two Features Does Kerberos Security Add to a Hadoop

Multiple Choice

Which two features does Kerberos security add to a Hadoop cluster? (Choose two)

A) User authentication on all remote procedure calls (RPCs)
B) Encryption for data during transfer between the Mappers and Reducers
C) Encryption for data on disk ("at rest")
D) Authentication for user access to the cluster against a central server
E) Root access to the cluster for users hdfs and mapred but non-root access for clients