Final answer:
A scrim (option 1) is a gauze or cloth screen that appears solid when painted and lit from the front, but becomes transparent when lit from behind.
Step-by-step explanation:
The gauze or cloth screen that appears solid when painted and lit from the front, but becomes transparent when lit from behind, is called a scrim.
This technique is commonly used in theater productions to create visual effects, such as changing scenery or creating illusions. When painted and lit from the front, the scrim appears solid and opaque, but when lit from behind, the light passes through the loosely woven fabric, making it transparent.
For example, a scene with actors positioned behind a scrim can create the illusion of characters appearing and disappearing as the lighting changes.