A user has created a subnet in VPC and launched an EC2 instance

A user has created a subnet in VPC and launched an EC2 instance within it. The user has not selected the option to assign the IP address while launching the instance. The user has3 elastic IPs and is trying 　　to assign one of the Elastic IPs to the VPC instance from the console. The console does not show any instance in the IP assignment screen. What is a possible reason that the instance is unavailable in the assigned IP console

A.THE IP ADDRESS MAY BE ATTACHED TO ONE OF THE INSTANCES

B.THE IP ADDRESS BELONGS TO A DIFFERENT ZONE THAN THE SUBNET ZONE

C.THE USER HAS NOT CREATED AN INTERNET GATEWAY

D.THE IP ADDRESSES BELONG TO EC2 CLASSIC; SO THEY CANNOT BE ASSIGNED TO VPC

正确答案是D