Which essential characteristic of cloud computing, as defined by NIST, refers to a consumer's ability to automatically provision computing resources without requiring human interaction with the cloud service provider?

On-Demand Self-Service is the NIST-defined characteristic describing a consumer's ability to unilaterally provision computing capabilities — such as server time or network storage — automatically, as needed, without requiring human interaction with each service provider. Resource Pooling refers to the provider's ability to serve multiple consumers using shared physical resources, Broad Network Access refers to availability over standard network channels, Rapid Elasticity refers to the ability to quickly scale resources up or down, and Measured Service refers to usage being automatically monitored and billed.