Can I change the EC2 security groups after an instance is launched in EC2-Classic?

Can I change the EC2 security groups after an instance is launched in EC2-Classic?
A . Yes, you can change security groups after you launch an instance in EC2-Classic.
B . No, you cannot change security groups after you launch an instance in EC2-Classic.
C . Yes, you can only when you remove rules from a security group.
D . Yes, you can only when you add rules to a security group.

Answer: B

Explanation:

After you launch an instance in EC2-Classic, you can’t change its security groups.

However, you can add rules to or remove rules from a security group, and those changes are automatically applied to all instances that are associated with the security group.

Reference: http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/using-network-security.html