Which solution achieves this goal?
Use EC2 instances in a single Availability Zone.
Use EC2 instances in multiple AWS Regions.
Use EC2 instances in multiple Availability Zones in the same AWS Region.
Use EC2 instances in the same edge location and the same AWS Region.
Explanations:
Using EC2 instances in a single Availability Zone does not provide redundancy in power sources, as all instances would be relying on the same physical infrastructure.
Using EC2 instances in multiple AWS Regions would place them in different geographic areas, which does not fulfill the requirement of sharing the same geographic area while using independent power sources.
Using EC2 instances in multiple Availability Zones within the same AWS Region allows the instances to share the same geographic area while being powered by different, independent power sources, thus providing fault tolerance.
Using EC2 instances in the same edge location and the same AWS Region would not provide independent power sources, as edge locations are designed for content delivery and not for running EC2 instances.
If I had to guess, I’d say the answer is:
Use EC2 instances in multiple Availability Zones in the same AWS Region.