Which solution achieves this goal?

Explanations:

Using EC2 instances in a single Availability Zone does not provide high availability; if that zone experiences a failure or disaster, all instances will be affected.

Deploying EC2 instances in multiple AWS Regions ensures that even if one region faces a disaster, instances in other regions will remain operational, thus providing high availability.

Using EC2 instances in multiple edge locations does not provide high availability in the context of natural disasters affecting the primary geographic regions, as edge locations primarily enhance content delivery rather than redundancy for instances.

Amazon CloudFront is a content delivery network (CDN) and does not provide high availability for EC2 instances themselves; it only helps with distributing content, not redundancy in case of a disaster.