The correct answer is B, which is to use EC2 instances in multiple AWS Regions. This approach ensures high availability by distributing instances across different geographical locations. If a natural disaster occurs in one region, the instances in other regions will continue to operate, providing uninterrupted service. This method offers a higher level of fault tolerance and disaster recovery compared to deploying instances in a single Availability Zone or multiple edge locations, or using Amazon CloudFront with EC2 instances as the source.