Option C is correct because an Artifact is designed for substantial, self-contained output that users need to inspect, edit, preview, and refine separately from the surrounding conversation. A landing-page prototype—particularly one containing HTML, CSS, JavaScript, or an interactive component—is more usable in a dedicated Artifact workspace than as code buried inside a chat response.
Artifacts support iterative development. The product manager can ask Claude to change the layout, copy, colors, component behavior, or responsive structure while maintaining a recognizable working version. The resulting prototype can also be reviewed or shared more effectively because it is presented as a distinct deliverable rather than as part of the conversation transcript.
Option A is a research workflow and would be appropriate for gathering sourced information about competitors, not for producing the prototype itself. Option B provides no dedicated editing or preview environment and makes repeated revisions harder to manage. Option D could preserve recurring instructions and reference materials, but a Project is a contextual workspace rather than the output format for the prototype.
A Project and an Artifact can be used together: the Project supplies persistent product requirements and design references, while the Artifact contains the actual prototype that the team iterates on.