The correct selection is C. Package development requires the Dev Hub packaging capability for unlocked and second-generation managed packages. Enabling that combined setting supports creation and versioning of package artifacts; source tracking alone or an imagined unlocked-only setting does not establish the full package-development capability. From a build perspective, the implementation should be source-driven, reviewable, automatable, and modular. Engineering controls such as version control, package boundaries, static analysis, coding standards, and isolated development environments reduce defects early and make changes easier to understand, test, and promote. The alternatives do not create the same repeatable engineering control: they either postpone defect detection, couple teams unnecessarily, or bypass the package/source model that should govern the change. For this scenario, the decisive point is therefore the platform behavior represented by the selected option (C. In setup, switch the Enable Unlocked Packages and Second-Generation Managed Packages to Enabled.). Applying that rule consistently keeps the implementation aligned with Salesforce-supported lifecycle practices and makes the resulting change easier to review, validate, and operate across environments.

Study Guide reference: Building — Salesforce DX; package development; coding standards; static analysis; source control; secure development.