How can the customer reduce the cost of IBM I licenses for the E880?

A customer with several Power770 systems runs a mixed production environment of Linux, AIX, and IBM i. They would like to purchase a single E880 for high availability, but are concerned about software licensing costs for IBM i.

How can the customer reduce the cost of IBM I licenses for the E880?
A . Use PowerHA System Mirror to transfer the licenses when needed.
B . Designate the system as Capacity BackUp (CBU) for IBM I
C . Use DLPAR to add already-activated cores to the IBM I partitions only when needed.
D . Enter the IBM i software keys from one of the production systems within 70 days of the failover.

Answer: B