A developer is testing an AWS Lambda function by using the AWS SAM local CLI.

When using AWS SAM local (sam local invoke, sam local start-api), the Lambda code runs in a local container on the developer’s machine. If that code uses the AWS SDK to call AWS services, it needs AWS credentials available in the local environment. The recommended way is to rely on the AWS SDK’s standard credential provider chain, which includes credentials stored by the AWS CLI in ~/.aws/credentials and selected via a named profile .

By running aws configure --profile < profileName > , the developer creates a dedicated set of access keys (and optionally a session token/region) for the test account. Then, running SAM with sam local invoke --profile < profileName > causes SAM to supply those credentials to the local container so the function can authenticate to AWS and make real API calls in the intended test account. This approach is clean, repeatable, and avoids hardcoding secrets into templates or source code.

Option A is insecure and not the intended use of SAM templates; templates are infrastructure definitions, not secret stores. Option C sets the Lambda execution role for deployed functions in AWS, but it does not automatically grant credentials to code running locally on a laptop. Option D misuses --parameter-overrides, which is meant for overriding template parameters at deployment/build time, not for securely injecting AWS access keys into local execution.

Therefore, the correct approach is B : configure an AWS CLI profile and run SAM local with the --profile option so the Lambda code can call AWS APIs in the test account using standard credential handling.