The study guide identifies B. Install SLDS Validator extension for VS Code as the correct answer.
The issue occurs during development in VS Code and specifically involves CSS classes and properties that conflict with SLDS. The answer therefore points to a development-time validation tool integrated with the environment where the developers are writing their code.
The SLDS Validator is the option in the study guide intended to simplify identifying SLDS-related problems while building Lightning Components. This makes it more appropriate than introducing an unrelated package or a designer-focused tool.
Option A, an SLDS creator from AppExchange, is not the tool selected by the guide for CSS validation within VS Code.
Option C, the Lightning Design System Plugin for Sketch, supports visual design and prototyping workflows rather than validating CSS implementation inside a development editor.
The distinction is between design tooling and implementation validation. Once developers are actively building a custom Lightning component and need to keep its styles aligned with SLDS conventions, the source specifies the VS Code SLDS Validator as the appropriate resource.
Study Guide reference/topics: SLDS Validator, VS Code, CSS, Lightning Components, Salesforce Lightning Design System.
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