The configuration of the AWS agent's polling interval for the CloudWatch API is managed at the agent instance level. In IBM's monitoring solutions, such as IBM Cloud Application Performance Management (APM) or its successors, the standard practice for monitoring multiple AWS regions is to create and configure a separate agent instance for each region. Each of these instances has its own configuration file where parameters like the CloudWatch polling interval can be set independently. Therefore, the polling interval can be effectively configured at the Region level.

A. Resource group: An AWS Resource Group is a logical collection of resources for organizational purposes and is not a level at which agent polling intervals are configured.

C. Account: While the agent is configured to access an AWS account, the polling interval is a more granular setting within a specific agent instance, not a global setting for the entire account.

D. Service: Although some monitoring tools allow per-service polling rates, the primary configuration model for the relevant IBM agents involves creating instances that target a specific region, making Region the configurable level.

1. IBM Documentation - Monitoring Agent for Amazon EC2: In the section on configuring the agent, the documentation states, "You can create multiple instances of this agent to monitor different AWS regions." Each instance has its own configuration, including the polling interval.

Source: IBM Documentation, Monitoring Agent for Amazon EC2, "Configuring the agent". (This principle applies to IBM's agent-based monitoring architecture for cloud services).

2. IBM Documentation - Configuration parameters for the Amazon EC2 agent: The documentation lists KECCLOUDWATCHINTERVAL as the "Interval in minutes for collecting CloudWatch data." This parameter is set per agent instance. Since each instance can be configured for a different region, the interval is effectively set at the region level.

Source: IBM Documentation, Monitoring Agent for Amazon EC2, "Configuration parameters for the Amazon EC2 agent".