Answer: A
AWS Budget: AWS Budget enables setting alerts via setting up custom budgets so that we are notified when cost and usage are forecasted to exceed or if cost and usage exceeds.
AWS Cost Explorer: AWS Cost Explorer helps analyze the usage and cost incurred over time by visualization through an easy to use interface.
AWS Savings plan: AWS Savings plan is a pricing model designed to offer up to 72% of savings to customers on compute usage of Amazon EC2, Amazon Fargate, and AWS Lambda.
AWS Organization: AWS Organization provides capabilities to centrally perform management and governance of billing, compliance adherence, security, resource sharing and access control.
Option A is CORRECT. AWS Budget and AWS Cost Explorer should be used.
Option B is INCORRECT.
Option C is INCORRECT.
Option D is INCORRECT.
Reference:
https://aws.amazon.com/aws-cost-management/aws-budgets/
https://aws.amazon.com/aws-cost-management/aws-cost-explorer/
https://aws.amazon.com/savingsplans/
https://aws.amazon.com/organizations/faqs/