The requirement is to continuously scan all AWS resources in this solution for security vulnerabilities with the least operational overhead. The environment includes Amazon EKS worker nodes in a managed node group and an Amazon ECR repository that stores container images used by the EKS cluster.

Amazon Inspector is a managed vulnerability scanning service that integrates directly with multiple AWS resource types. It can automatically discover Amazon EC2 instances (including EKS managed node group instances) and perform continuous vulnerability assessments against them, using software inventory and known CVE databases. Inspector also integrates with Amazon ECR to scan container images for vulnerabilities when images are pushed to the repository and periodically thereafter, providing continuous assessment of image security posture without requiring separate scanners or infrastructure.

By activating Amazon Inspector for the account and region, the service will automatically start tracking supported resources, including EKS-managed EC2 instances and ECR repositories, and will begin scanning them for known vulnerabilities. Findings are provided through the Inspector console and can be integrated with other services such as AWS Security Hub or Amazon EventBridge for further aggregation and automation, but no separate infrastructure deployment or maintenance is required.

Option B, therefore, provides end-to-end vulnerability scanning for both the EKS nodes and the ECR images with minimal operational overhead, because it leverages a fully managed AWS service that automatically discovers and scans supported resources.

Option A is not correct because AWS Security Hub does not itself perform vulnerability scanning. Security Hub aggregates and normalizes security findings from various AWS services, including Amazon Inspector, GuardDuty, and others. It is a security posture management and aggregation service, not a vulnerability scanner.

Option C introduces additional operational overhead by requiring the company to provision, configure, secure, and maintain a separate EC2 instance running a third-party vulnerability scanning tool. While ECR basic scan-on-push can detect some image vulnerabilities, the EC2-based scanner must be managed, updated, and scaled by the customer, which violates the requirement for the least operational overhead when a fully managed alternative exists.

Option D is incorrect because the Amazon CloudWatch agent is used for metrics and log collection from EC2 instances and other environments; it does not perform vulnerability scanning or CVE analysis. Configuring CloudWatch for monitoring and logging does not meet the requirement to continuously scan for security vulnerabilities. ECR basic scans also provide only image-level scanning and do not cover the EKS nodes themselves.

Therefore, enabling Amazon Inspector to scan both the EKS nodes and the ECR repository, as described in option B, is the solution that meets the continuous vulnerability scanning requirement with the least operational overhead.