A Company Has an Application That Generates Invoices and Makes

A company has an application that generates invoices and makes the invoices available online. Invoices are stored as PDFs in an Amazon S3 bucket. Customers typically only view each invoice during the month it is issued. However, past invoices need to be immediately available. There are concerns over rising storage costs as the company gains more customers. What is the MOST cost-effective method to store the data?

A) Use Amazon S3 for current invoices. Set up lifecycle rules to migrate invoices to the GLACIER storage class after 30 days.
B) Store the invoices as text files. Use Amazon CloudFront to convert the invoices from text to PDF when customers download invoices.
C) Store the invoices as binaries in an Amazon RDS database instance. Retrieve them from the database when customers request invoices.
D) Use Amazon S3 for current invoices. Set up lifecycle rules to migrate invoices to Amazon S3 Standard-Infrequent Access (S3 Standard-IA) after 30 days.