What characteristic of cloud computing employs a "pay-per-use" metering method?

The characteristic of cloud computing that employs a "pay-per-use" metering method is referred to as measured service. This concept allows users to monitor and control their usage of cloud resources in a way that directly reflects the amount of service consumed. It enables businesses to scale their operations according to demand without incurring unnecessary costs.

In a measured service model, resources are automatically monitored and reported, ensuring that users only pay for what they actually utilize. This feature is essential in cloud environments as it provides transparency and efficiency in cost management. Users can access detailed reports on resource usage, which facilitates budgeting and financial planning.

The other options, while important aspects of cloud computing, do not specifically address the metering and billing model. Rapid elasticity refers to the ability to quickly scale resources up or down as needed, on-demand self-service allows users to provision resources automatically without human intervention, and resource pooling denotes the multi-tenant model where resources are pooled to serve multiple clients. None of these directly involve the pay-per-use billing mechanism that is central to measured service.