A document platform serves immutable public images globally. The origin receives repeated requests for the same content and users report high cross-continent latency. What design most directly improves both origin load and delivery latency?

1. Disable caching globally and increase DNS TTL only.
2. Add every request header and unique request ID to the cache key.
3. Use CloudFront with appropriate cache keys, TTLs, and versioned asset URLs.
4. Place all images on one EC2 instance with no distribution layer.