Which of the following statements is false when it comes to the Elastic Network Interface?

Answer options:

A.You can attach a network interface to an instance when it`s running
B.You can detach the secondary network interface and attach it to another instance in the same subnet.
C.You can detach the Primary network interface and attach it to another instance in the same subnet.
D.You have a secondary private IP for a Network Interface

Answer - C
The AWS documentation mentions the following on some of the points regarding Elastic Network Interfaces
1)You can attach a network interface to an instance when it`s running (hot attach), when it`s stopped (warm attach), or when the instance is being launched (cold attach).
2)You can detach secondary (ethN) network interfaces when the instance is running or stopped. However, you can`t detach the primary (eth0) interface.
3)You can attach a network interface in one subnet to an instance in another subnet in the same VPC; however, both the network interface and the instance must reside in the same Availability Zone.
For more information on the Elastic Network Interface, please visit the below link:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html