Answer the following question given this paragraph: 

Besides entertaining a cat, laser light has many other uses. It is used to scan bar codes, for example, and to carry communication signals in optical fibers. Optical fibers are extremely thin glass tubes that are used to guide laser light (see Figure below ). Sounds or pictures are encoded in pulses of laser light, which are then sent through an optical fiber. All of the light reflects off the inside of the fiber, so none of it escapes. As a result, the signal remains strong even over long distances. More than one signal can travel through an optic fiber at the same time, as you can see in Figure below . Optical fibers are used to carry telephone, cable TV, and Internet signals.


Q: What do optical fibres look like?

 Choices:

- square boxes

- big flashlights

- flat paper

- thin glass tubes

A:
thin glass tubes
