What happens if the rear inner boundary of a transparent bottle is drawn as dark as the front boundary?

Correct answer: Interior and exterior depth will become unclear

The governing concept is selective line emphasis in transparent forms. The front boundary is usually clearer because it is nearer or more visually dominant, while a rear inner edge is often lighter or partially interrupted by the transparent surface. Making both equally dark gives every boundary the same visual weight, flattening the layers and making it difficult to tell what is inside, behind, or outside. It does not increase transparency or shrink the bottle, so option D is correct.