The correct answer is C. AWS Regions. AWS Regions are geographically distinct locations where AWS services, including EC2 instances, are available. By deploying EC2 instances in a region that is geographically close to the company's global users, the company can reduce latency and improve the performance of their applications. Availability Zones (A) are distinct locations within a region that provide high availability and durability, but they are not separate geographical locations. Edge locations (B) are endpoints for AWS services like Amazon CloudFront and are used for caching and distributing content, not for running EC2 instances. Regional edge caches (D) are a feature of Amazon CloudFront that caches content at the edge of the network, closer to the viewer, but they are not related to running EC2 instances.