You are using Cloud CDN to deliver static HTTP(S) website content hosted on a Compute Engine instance group. You want to improve the cache hit ratio. What shoul...

You are using Cloud CDN to deliver static HTTP(S) website content hosted on a Compute Engine instance group. You want to improve the cache hit ratio.
What should you do?

A. Customize the cache keys to omit the protocol from the key. B. Shorten the expiration time of the cached objects. C. Make sure the HTTP(S) header "Cache-Region" points to the closest region of your users. D. Replicate the static content in a Cloud Storage bucket. Point CloudCDN toward a load balancer on that bucket.