Which AWS service will satisfy these requirements?

Explanations:

AWS Budgets allows users to set custom cost and usage budgets. It can send alerts via email when spending approaches or exceeds preset thresholds, making it the best solution for this requirement.

AWS Cost Explorer is a tool for visualizing and analyzing AWS costs and usage over time. It does not provide the ability to create alerts for cost thresholds.

AWS Trusted Advisor provides best practice recommendations for improving AWS account configurations but does not include features for alerting on cost or usage limits.

AWS Cost and Usage Report provides detailed billing and usage data but does not offer alerting features for cost thresholds. It is useful for cost analysis but not for managing alerts.