What might cause the registration was rejected?

The customer plans to buy a new E870, as the primary server has been installed 740, customers will migrate IBMi 740 partitions, operating system license and software to E870, they need 740 into a CBU. When trying to register 740 as a CBU backup machine, be refused registration.

What might cause the registration was rejected?
A . CBU total CPW rating system must be at least as high as the main system.
B . the software level is not the same on both systems.
C . CBU function only when purchasing a new server or by model/type upgrade.
D . the main system to IBMi kernel total amount is higher.

Answer: B