Final answer:
For the lowest latency in delivering image files globally, Amazon CloudFront, a content delivery network (CDN), is the best AWS service as it caches content at edge locations near end users.
Step-by-step explanation:
To deliver image files with the lowest latency to end users around the world and ensure the best possible performance for an online photo sharing service, the appropriate AWS service to use is Amazon CloudFront. This is a content delivery network (CDN) that securely delivers data, videos, applications, and APIs to customers globally with low latency and high transfer speeds, all within a developer-friendly environment. Amazon CloudFront works by caching content at edge locations closest to the end users, significantly reducing the time required to serve content by serving it from a location near the user. When an end user requests content that is served by CloudFront, the service automatically routes the request to the edge location with the lowest latency.