The correct answer is C. Import Lightning stylesheets in Visualforce, according to the uploaded study guide.
The scenario is specifically about an organization that has not yet migrated to Lightning Experience but still wants custom Salesforce applications to present a Lightning-consistent visual appearance.
Within the study-guide framing, importing Lightning stylesheets into Visualforce provides the appropriate bridge between legacy Visualforce applications and the visual language associated with Lightning Experience.
Option A references an SLDS package, but the question is not asking how to build an independent front-end application using package-managed CSS resources. It asks for the Salesforce-based solution appropriate to the existing Visualforce context.
Option B, importing standard design tokens into a stylesheet, would not by itself reproduce the broader Lightning component styling required to give the application a consistent Lightning appearance.
The essential UX objective is visual consistency across platform generations. Users should encounter familiar spacing, typography, control treatments, and general presentation even when some applications remain on older Salesforce technology.
The study guide therefore points to Visualforce's ability to use Lightning styling as the appropriate way to achieve this transition-oriented design requirement.
Study Guide reference/topics: SLDS, Visualforce, Lightning Experience styling, legacy application consistency, Salesforce Lightning Design System.
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