Which factor primarily influences attenuation in optical fiber systems?

Attenuation in optical fiber systems is primarily influenced by the physical environment. This factor encompasses various conditions such as temperature variations, humidity, and any physical stress that the fiber may encounter during installation and operation.

The materials used in the fiber construction can also affect how light signals degrade as they travel through the fiber. Factors like bend radius, proximity to electromagnetic interference, and exposure to certain chemicals in the environment can lead to increased signal loss, contributing to overall attenuation.

While voltage levels and installation practices can affect the performance of electrical systems, they do not have a direct impact on optical fiber attenuation. The integrity and characteristics of the physical environment are therefore the key determinants in how much signal loss occurs, making this the correct answer to the question.