To protect against a Regional failure, the application must be deployed in multiple Regions. Amazon Route
53 DNS failover with health checks allows traffic to be automatically routed to a healthy Region when the primary becomes unavailable, meeting high availability and disaster recovery requirements.
Reference: AWS Well-Architected Framework - Multi-Region High Availability with Route 53 Health Checks

D is the best match because AWS Lambda is a serverless compute service that runs code without provisioning or managing servers, which directly aligns with the requirement for minimal infrastructure and minimal operational support. Lambda supports Python runtimes, so the team can deploy the selected component as a microservice using the same language. For workloads with hundreds of requests per second, Lambda is designed to handle request-driven execution and automatically scales by running more concurrent instances of the function in response to incoming traffic, without the customer needing to pre-size or manage capacity.
The other options introduce significantly more operational responsibility. Option A still requires managing EC2 instances (AMI lifecycle, patching, capacity planning, scaling policies) and Spot interruptions can add complexity for a web microservice test. Option B (Elastic Beanstalk) reduces some management overhead but still relies on underlying instances and environment management (platform updates, scaling configuration, health monitoring), and it is not a serverless model. Option C (EKS with self-managed nodes) has the highest operational burden here: cluster and node management, scaling node groups, patching, and Kubernetes operations-this conflicts with "minimal operational support." Lambda fits the serverless microservices goal: deploy code as small independent services, integrate with other managed services (commonly API-driven invocation patterns), and rely on AWS-managed scaling and availability mechanisms rather than administering fleets or clusters.

Amazon RDS Multi-AZ deployment provides automated failover and increased availability for MySQL databases. In case of infrastructure failure or power outage in one Availability Zone, RDS automatically fails over to a standby replica in another AZ, minimizing downtime. This is the AWS-recommended way to achieve high availability for relational databases.
AWS Documentation Extract:
"Amazon RDS Multi-AZ deployments provide high availability, failover support, and data redundancy for database instances. In the event of infrastructure failure, Amazon RDS performs an automatic failover to the standby." (Source: Amazon RDS documentation, High Availability) A: An ALB does not increase availability for a single database instance.
B: EC2 instance recovery does not move the instance across Availability Zones.
D: Termination protection prevents accidental deletion, not availability issues.
Reference: AWS Certified Solutions Architect - Official Study Guide, RDS High Availability.

IAM user creation and deletion are AWS API management events. CloudTrail records management events such as IAM CreateUser and DeleteUser API calls. EventBridge can match these CloudTrail events with an event pattern and route the matching events to an Amazon SNS topic. Subscribing the company's email address to the SNS topic provides the required email notification. Amazon Inspector is for vulnerability and exposure findings, not IAM account-change monitoring. GuardDuty can detect suspicious IAM behavior, but it is not the correct service for deterministic notifications every time a user is created or deleted. Amazon Macie is focused on sensitive data discovery and data security findings in services such as Amazon S3, not IAM lifecycle events.