Which of the following describes a fixed lens?

A fixed lens is characterized by having a specific focal length and does not allow for adjustments to zoom in or out. This means that it provides a consistent field of view, which is useful in situations where a specific perspective is required and doesn't need to change frequently. Fixed lenses often offer better image quality due to the simpler optical design and reduced number of moving parts compared to zoom lenses.

In contrast, a lens with variable focal length, as mentioned in the first option, would provide adjustable zoom capabilities, which is not a characteristic of fixed lenses. The third option incorrectly limits the application of a fixed lens to only wide-angle shots; fixed lenses, in reality, can come in various focal lengths including standard, telephoto, and macro, covering a wide range of photographic needs. Lastly, the fourth option inaccurately describes a fixed lens, as it is fully capable of focusing light to form clear images. Therefore, the definition of a fixed lens aligns perfectly with the characteristic of having a fixed focal length.