What is one cause of this?

A new Amazon Redshift Spectrum Cluster has been launched for a team of Business Analysis. When the team attempts to use the cluster to query the data in Amazon S3, they receive the following error:

What is one cause of this?
A . The cluster has Enhanced VPC Routing enabled and it must be turned off
B . The cluster is only a single node and needs to be expanded to multi-node.
C . The cluster login credentials are incorrect request new credentials from the Administrator
D . The cluster nodes are running in multiple Availability Zones, and all need to be placed in a single Availability Zone.

Answer: C