What should the solutions architect recommend?
Launch an Amazon EC2 instance in us-east-1 and migrate the site to it.
Move the website to Amazon S3. Use Cross-Region Replication between Regions.
Use Amazon CloudFront with a custom origin pointing to the on-premises servers.
Use an Amazon Route 53 geoproximity routing policy pointing to on-premises servers.
Explanations:
Launching an EC2 instance in us-east-1 does not address the latency issues for European users, as the backend remains in the US and does not optimize content delivery to Europe.
Moving the website to Amazon S3 and using Cross-Region Replication would not provide immediate performance benefits for European users since replication is for data availability and not for low-latency access.
Using Amazon CloudFront allows for caching content closer to European users, significantly reducing loading times. CloudFront can serve cached copies of the website while the backend remains in the US.
Amazon Route 53 geoproximity routing can help with traffic management but does not inherently improve loading times. It routes users to the closest servers, which are still the on-premises servers in the US, potentially resulting in high latency for European users.
As far as I can tell, the answer is:
Use Amazon CloudFront with a custom origin pointing to the on-premises servers.