An administrator runs mktcpip aixhost 172.168.0.50 enO to change the network address， but the command hangs for an extended period of time. Which of the following is the most likely cause of the problem（）
- AentO is in a defined state
- BenO is currently active
- CThere is no physical network adapter on the system
- DThe address 172.168.0.50 is in use by another system