Final answer:
Correct option: b. transmission
The passage of light through an object is transmission, while the bending of light when it passes from one medium to another is called refraction. The process enabling light to travel through a non-straight tube is total internal reflection of light.
Step-by-step explanation:
The passage of light through an object is known as transmission. This is distinct from light being absorbed, which is when the object soaks up the light, or reflected, where the light bounces off the surface. Refraction is another phenomenon where light changes direction when passing from one medium to another, like air to glass. When light and images travel through a tube that is not straight, the process allowing this is called total internal reflection of light. This phenomenon occurs when the light reflects completely within the boundary of a denser medium, like water or glass, without getting refracted out when it hits the boundary at a certain critical angle.