Amazon CloudWatch is the AWS service designed for monitoring operational metrics and collecting performance data. It provides metrics for various AWS resources including EC2 instances (CPU utilization, disk I/O), RDS databases, and other services. CloudWatch enables users to collect and track metrics, collect and monitor log files, set alarms, and automatically react to changes in AWS resources.

Key features of Amazon CloudWatch:

• Metrics Collection: Collects operational metrics from AWS services
• Monitoring: Monitors CPU utilization, network traffic, disk I/O, and other performance indicators
• Alarms: Allows setting alarms to notify when metrics breach thresholds
• Dashboards: Provides customizable dashboards for visualizing metrics

Comparison with other options:

• AWS CloudTrail: Records API calls and user activity for auditing and compliance
• AWS Config: Tracks resource configurations and changes over time
• AWS Trusted Advisor: Provides recommendations for cost optimization, security, and performance improvements

Therefore, Amazon CloudWatch is the correct answer for monitoring operational metrics like CPU utilization, latency, and disk I/O.