A database specialist is designing an application to answer one-time queries. The application will query complex customer data and provide reports to end users. These reports can include many fields. The database specialist wants to give users the ability to query the database by using any of the provided fields.
The database's traffic volume will be high but variable during peak times. However, the database will not have much traffic at other times during the day.
Which solution will meet these requirements MOST cost-effectively?

A. Amazon DynamoDB with provisioned capacity mode and auto scaling
B. Amazon DynamoDB with on-demand capacity mode
C. Amazon Aurora with auto scaling enabled
D. Amazon Aurora in a serverless mode