What type of system is NOT affected by electromagnetic interference (EMI)?

Optical fibers are immune to electromagnetic interference (EMI) because they transmit data as light rather than electrical signals. This fundamental difference means that external electromagnetic fields, which typically induce noise and interference in metal-based transmission systems, do not impact the transmission of light within the fiber.

In contrast, coaxial and twisted pair cables rely on electrical signals to transmit data, making them susceptible to EMI, which can introduce noise and reduce signal quality. Wireless systems, while they utilize radio waves that can theoretically be affected by EMI, they can also encounter interference because of the presence of other radio signals. However, optical fibers maintain their signal integrity by purely relying on light transmission, which is unaffected by electromagnetic fields, thereby making them the correct choice in this context.