A given public AMI can:

EC2 instances are launched from Amazon Machine images (AMIS). A given public AMI can:

A.
be used to launch EC2 Instances in any AWS region.

B.
only be used to launch EC2 instances in the same country as the AMI is stored.

C.
only be used to launch EC2 instances in the same AWS region as the AMI is stored.

D.
only be used to launch EC2 instances in the same AWS availability zone as the AMI is stored.