You are building a system to distribute confidential training videos to employees. using cloudfront, what method could be used to serve content that is stored in s3, but not publically accessible from s3 directly?
(a) create an origin access identity (oai) for cloudfront and grant access to the objects in your s3 bucket to that oai.
(b) add the cloudfront account security group "amazon-cf/amazon-cf-sg" to the appropriate s3 bucket policy.
(c) create an identity and access management (iam) user for cloudfront and grant access to the objects in your s3 bucket to that iam user.
(d) create a s3 bucket policy that lists the cloudfront distribution id as the principal and the target bucket as the amazon resource name (arn).