Overall explanation Correct option:

Create a new cache policy for the CloudFront distribution and set the cache behavior to Query string forwarding and caching. In the Query string whitelist field include the language string. Update the CloudFront distribution to use the new cache policy

CloudFront can cache different versions of your content based on the values of query string parameters. Forward all, cache based on whitelist option should be chosen if your origin server returns different versions of your objects based on one or more query string parameters. Then specify the parameters that you want CloudFront to use as a basis for caching in the Query string whitelist field.

Incorrect options:

Create a new cache policy for the CloudFront distribution and set the cache behavior to None to improve caching performance. Update the CloudFront distribution to use the new cache policy - None improves Caching. Choose this option if your origin returns the same version of an object regardless of the values of query string parameters. This increases the likelihood that CloudFront can serve a request from the cache, which improves performance and reduces the load on your origin.

Create a new cache policy for the CloudFront distribution and set the cache behavior to Cache based on selected request headers. Use Whitelist Headers as the caching criteria - Cache based on selected request headers is not a valid option since the use case mentions using query string parameters.

Choose the Customize option for the Object Caching setting and reduce the Default TTL value so that CloudFront forwards requests to your origin more frequently - Default TTL specifies the default amount of time, in seconds, that you want objects to stay in CloudFront caches before CloudFront forwards another request to your origin to determine whether the object has been updated. This option is irrelevant for the current use case since the response returned defaulting to the same language is not a TTL issue.