You had an Elastic IP address associated with an instance that was running for a period of 3 months. Now you have disassociated the Elastic IP address. But you can see that you are still being charged for the Elastic IP address. What can you do to ensure that you don’t get charged for the Elastic IP address? Choose 2 answers from the options given below

Answer options:

A.Explicitly release the Elastic IP from your account.
B.Quickly associate it with any stopped instance
C.Quickly associate it with any running instance
D.Associate it with an un-attached network interface

Answer - A and C
The AWS documentation mentions the following
A disassociated Elastic IP address remains allocated to your account until you explicitly release it.
To ensure efficient use of Elastic IP addresses, we impose a small hourly charge if an Elastic IP address is not associated with a running instance, or if it is associated with a stopped instance or an unattached network interface. While your instance is running, you are not charged for one Elastic IP address associated with the instance, but you are charged for any additional Elastic IP addresses associated with the instance.
For more information on Elastic IP’s , one can visit the below URL:
http://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/elastic-ip-addresses-eip.html