This solution requires two components: a deployment mechanism and an application design pattern.

Option C, using a CDK pipeline, provides the ideal deployment mechanism. CDK Pipelines (built on AWS CodePipeline) are purpose-built to automate deployments across multiple stages, which can be configured for different AWS accounts and Regions. This creates a consistent, repeatable process with the least manual effort, as deployments are triggered automatically from a source code repository.

Option B provides the best application design pattern. To be reusable, the CDK code should not contain hardcoded resource IDs. By using context methods like Vpc.fromLookup(), the CDK application can dynamically discover the IDs of existing resources (like VPCs and hosted zones) in the target account and Region during the synthesis stage. This makes the stack portable across any environment.

A. Using CloudFormation parameters is less dynamic than CDK context lookups for discovering existing resources and often requires more manual configuration per deployment.

D. A custom script is a less robust, less secure, and less manageable solution than a native, fully managed CDK Pipeline for CI/CD.

E. This describes a manual deployment process. Running cdk deploy with flags locally for each environment directly contradicts the requirement for automation and least manual effort.

1. AWS CDK Developer Guide, "CDK Pipelines: Continuous delivery for AWS CDK applications": This guide explains that CDK Pipelines are the recommended way to set up a robust, multi-account, multi-Region continuous deployment pipeline for CDK applications, which minimizes manual deployment steps. (Supports Option C).

2. AWS CDK Developer Guide, "Runtime context": This section details context providers. It states, "The AWS CDK can retrieve context from the AWS environment during synthesis." This includes looking up existing VPCs, Availability Zones, and Route 53 Hosted Zones, which is the mechanism described in Option B.

3. AWS CDK API Reference, awsec2.Vpc.fromLookup() method: The documentation for this static method explicitly states it is used to "Import a VPC from another stack or from the same stack by looking it up in the target account." This directly supports the lookup approach in Option B for using pre-existing network components.

4. AWS CDK Developer Guide, "Environments": This document clarifies that a CDK stack is deployed to a specific environment (account and Region). It explains how the CDK determines this context at runtime, which is essential for the context lookups in Option B to function correctly within the pipeline stages from Option C.