To preview a creative on a blank page, what option should be selected from the dropdown?

Blank page" is the correct option because it provides a clean, unadorned environment to preview the creative, allowing you to focus solely on its design and functionality without the distraction of other website content. "Custom URL" would embed the creative within a specified webpage, which might not be blank. "Sample website" would display the creative on a pre-defined, possibly irrelevant, website template. "On screen" is too general and doesn't specify the preview environment; it simply means the creative will be displayed.