You need to find the subnet, the security group and the VPC that your instance is associated with. Which of the following would be part of the set of commands that you would use first.

Answer options:

A.AWS vpc describe-all
B.AWS ec2 describe-security-groups
C.AWS ec2 describe-instances
D.AWS ec2 describe-network-acl

Answer - C
This command will give you the entire details about your instance which includes the subnet, VPC and security group associated with your instance
For more information on the command, please visit the below URL:
http://docs.aws.amazon.com/cli/latest/reference/ec2/describe-instances.html