Comprehensive and Detailed 250 to 300 words of Explanation (AWS documentation-based, no links):

The company wants to increase security and reduce operational overhead for SQL Server relational databases. The most direct AWS managed service for SQL Server is Amazon RDS for SQL Server, which offloads routine database administration tasks such as provisioning, backups, patching (within managed service controls), monitoring integrations, and high availability management compared with running SQL Server on self-managed EC2.

Choosing Multi-AZ enhances availability and resilience by maintaining a synchronous standby in a separate Availability Zone with automated failover. This improves overall security posture and operational reliability because the platform handles common infrastructure failure scenarios without requiring custom clustering or manual intervention.

For encryption of sensitive data, integrating RDS with AWS KMS allows encryption at rest using KMS keys. Using an AWS managed key is operationally simple while still providing strong encryption controls, auditability, and centralized key management.

Option A still requires managing the database on EC2 (OS patching, SQL Server patching, backups, HA design, monitoring, recovery), which increases operational overhead significantly. Option C is not a database migration approach; S3 plus Macie does not provide a relational SQL Server engine for applications. Option D changes the data model by moving to DynamoDB and does not preserve SQL Server relational capabilities; CloudWatch Logs is not a data security control for database content.

Therefore, B best satisfies the goals: a managed relational database service (RDS for SQL Server) with built-in high availability (Multi-AZ) and encryption at rest via KMS, reducing ongoing operational work while improving security controls.