Which combination of actions will meet these requirements?

Explanations:

Activating user-defined cost allocation tags allows the company to categorize and track costs based on the application and team responsible for each application, facilitating accurate cost attribution and reporting.

AWS-generated cost allocation tags do not typically include application or team-specific information unless they are specifically designed by AWS. Therefore, activating these tags would not meet the requirement to track costs by application and team.

Creating cost categories for each application in Billing and Cost Management enables the company to organize and report costs associated with each application, providing clarity in cost allocation and making it easier to compare and forecast costs.

While IAM access to Billing and Cost Management is important for managing permissions, it does not directly contribute to tracking costs or generating reports based on application or team. This action alone does not meet the specified requirements.

Creating a cost budget is useful for managing and forecasting costs but does not directly address the need for detailed reporting or cost attribution for applications and teams. This action does not fulfill the primary requirement of generating detailed cost reports.

Enabling Cost Explorer allows the company to visualize, analyze, and report on their costs over time. This tool supports the ability to compare costs from the last 12 months and aids in forecasting future costs, thereby fulfilling the requirement.