Final answer:
The component of Apache Ambari architecture that holds the cluster configurations is the Ambari Database, which interacts with the Ambari Server to manage the cluster's configuration states.
Step-by-step explanation:
The component of the Apache Ambari architecture that stores the cluster configurations is D. Ambari Database. Apache Ambari is a web-based tool for provisioning, managing, and monitoring Apache Hadoop clusters. Ambari consists of two main components: the Ambari Server and Ambari Agents. While the Ambari Server acts as the central management entity, the Ambari Agents run on all nodes and report back to the server. However, the configurations for the cluster are stored in the Ambari Database, which is accessed by the Ambari Server to maintain the state of the cluster configurations, as well as the state of the services running on the cluster.