Amazon Aurora is a cloud-native relational database service that combines the performance and availability of high-end commercial databases with the simplicity and cost-effectiveness of open-source databases. It is designed to be a drop-in replacement for existing databases and offers full compatibility with two popular open-source database engines: MySQL and PostgreSQL. This allows users to migrate their existing MySQL and PostgreSQL applications and workloads to Aurora with minimal to no code changes, while benefiting from its enhanced performance, scalability, and reliability.

A. Oracle: Amazon Aurora is not compatible with Oracle. For Oracle workloads, AWS offers Amazon RDS for Oracle.
B. Microsoft SQL Server: Amazon Aurora is not compatible with Microsoft SQL Server. AWS provides Amazon RDS for SQL Server for this engine.
E. MongoDB: MongoDB is a NoSQL database. Amazon DocumentDB (with MongoDB compatibility) is the relevant AWS service, not Aurora.

1. AWS Documentation - Amazon Aurora FAQs: Under the "General" section

the question "Q: What relational database engines does Amazon Aurora support?" is answered with: "Amazon Aurora is compatible with MySQL and PostgreSQL."

Source: AWS. (n.d.). Amazon Aurora FAQs. Retrieved from https://aws.amazon.com/rds/aurora/faqs/

2. AWS Documentation - What is Amazon Aurora?: The introductory section states

"Amazon Aurora is a global-scale relational database service built for the cloud

with full MySQL and PostgreSQL compatibility."

Source: AWS. (n.d.). What is Amazon Aurora?. AWS Documentation. Retrieved from https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/CHAPAuroraOverview.html

3. AWS Documentation - Amazon Aurora Features: The overview of features explicitly mentions its compatibility: "Amazon Aurora is a relational database management system (RDBMS) that is compatible with MySQL and PostgreSQL."

Source: AWS. (n.d.). Amazon Aurora Features. Retrieved from https://aws.amazon.com/rds/aurora/features/