A company has a Redshift cluster for petabyte-scale data warehousing. The data within the cluster is easily reproducible from additional data stored on Amazon S3. The company wants to reduce the overall cost of running this Redshift cluster. Which scenario would meet best for the needs of the running cluster? Choose the correct answer from the options below.

Answer options:

A.Disable automated backups. Create a read-replica in another region for disaster recovery.
B.Enable automated snapshots but set the retention period to a lower number to reduce storage costs.
C.Implement daily backups but do not enable multi-region copy to save data transfer costs.
D.Disable manual snapshots on the cluster.

Answer – B
Snapshots are point-in-time backups of a cluster. There are two types of snapshots: automated and manual. Amazon Redshift stores these snapshots internally in Amazon S3 using an encrypted Secure Sockets Layer (SSL) connection. If you need to restore from a snapshot, Amazon Redshift creates a new cluster and imports data from the snapshot that you specify.
Option A is incorrect because AWS Redshift does not have the concept of read replica.
Option B is CORRECT because 
"There is no additional charge for backup storage up to 100% of your provisioned storage for an active data warehouse cluster". Therefore, if we reduce to a 1-day retention period for the backup, we can save costs too. 
Refer link: https://aws.amazon.com/redshift/pricing/
Option C is incorrect because implementing daily backup is going to be more expensive than option
B.Option D is incorrect because we cannot get disabled manual snapshots. In this scenario, we need to reconfigure the automated snapshots.
For more information on Redshift snapshots, please visit the below URL-
http://docs.aws.amazon.com/redshift/latest/mgmt/working-with-snapshots.html