When can transparency still appear convincing if the front and rear edges of a glass vessel are equally clear?

Correct answer: When background contrast and reflections clarify both edges equally

Transparency is judged from several visual cues, not from edge sharpness alone. If the background provides contrast behind both edges and reflections are placed consistently on the glass surface, the front and rear contours can remain equally clear while the vessel still reads as transparent. Making every edge black, removing all shadows, or reducing the vessel’s size does not establish glass. Thus, option B is correct.