An on-premises Java web application uses MongoDB to store subscriber data. The company must migrate the application to AWS with the same architecture, deploy it for high availability, and cannot change the application code. Which AWS-based architecture will meet these requirements?

The correct option leverages Amazon DocumentDB (with MongoDB compatibility) because it provides a fully managed, highly available, and scalable database service that is compatible with MongoDB APIs. This allows the application to migrate without code changes, fulfilling a key requirement. Deploying DocumentDB across multiple Availability Zones ensures high availability for the database. Similarly, deploying the Java application on EC2 instances within an Auto Scaling group across multiple Availability Zones ensures high availability and scalability for the application tier. The other options are incorrect because: Using Amazon Aurora DB cluster would require significant application code changes as Aurora is a relational database, not a NoSQL document database. Running MongoDB on Amazon EC2 instances in a single Availability Zone would not meet the high availability requirement for the database. Using Amazon DocumentDB in on-demand capacity mode is not the primary factor for meeting the "appropriately sized instances" requirement, which implies provisioning for performance. While on-demand can be used, "appropriately sized instances" is more direct for performance and cost optimization.