Which solution meets these requirements?

Explanations:

Adjusting the TTL value for the DNS CNAME record will not affect the content already cached by CloudFront. DNS TTL only controls how long DNS resolvers cache the DNS entry, not the content served by CloudFront.

Creating an invalidation on the CloudFront distribution for the old S3 objects will force CloudFront to fetch the latest content from the S3 bucket, making the updated website visible to users immediately. This is the most efficient solution to update the content seen by users.

Creating a new CloudFront distribution and updating DNS records would require additional time for propagation and may not be necessary. It is more complex and does not directly resolve the issue of outdated cached content, as it still would not address the old objects in the current distribution.

Updating the DNS record to point to the S3 bucket instead of the CloudFront distribution would negate the benefits of using CloudFront, such as caching and global distribution. Users would still see the cached content from CloudFront until the cache expires, which does not resolve the immediate visibility of the new content.