Answer: Cluster virtual machines

When a customer initiates a Spark cluster, the virtual machines for the cluster are deployed in the data plane within the customer's cloud account. This is a fundamental aspect of the Databricks Lakehouse architecture, ensuring that compute resources are managed within the customer's own cloud environment. Reference: [Databricks Documentation](https://docs.databricks.com/getting-started/overview.html)

Author: LeetQuiz Editorial Team