A company needs to start using a Redshift cluster. They have 10 GB of data. They don’t know the cluster size that should be used for the cluster. They have not done any testing to come to the recommended cluster size. Which of the following would be the ideal way to provision the Redshift cluster in a cost-efficient manner?

Answer options:

A.Create the cluster with a large number of cluster nodes
B.Create the cluster with a small number of cluster nodes
C.Insist on doing the testing to come up with the base requirement for the number of clusters
D.Plan on purchasing Reserved capacity

Answer – B
To be cost efficient you can start with a minimum number of nodes for the cluster
The AWS Documentation mentions the following
If your storage and performance needs change after you initially provision your cluster, you can resize your cluster. You can scale the cluster in or out by adding or removing nodes. Additionally, you can scale the cluster up or down by specifying a different node type.
For example, you can add more nodes, change node types, change a single-node cluster to a multinode cluster, or change a multinode cluster to a single-node cluster. However, you must ensure that the resulting cluster is large enough to hold the data that you currently have or else the resize will fail. 
Option A is incorrect since this would not be a cost-effective option
Option C is incorrect since , even though possible , it’s is sometimes difficult to come up with a benchmark, that is why you can have a flexible infrastructure setup with the service
Option D is incorrect since we don’t the requirement , we cannot plan to buy reserved instances at the start
For more information on working with clusters, please refer to the below URL
https://docs.aws.amazon.com/redshift/latest/mgmt/working-with-clusters.html