Which statement about fiber-optic cable is true?

• A. It is not affected by EMI or RFI.
• B. Each pair of cables is wrapped in metallic foil.
• C. It combines cancellation, shielding, and twisting to protect data.
• D. It typically contains 4 pairs of fiber-optic wires.

Answer: (A)

Signals in fiber-optic cables are carried as light through a glass or plastic core, not as electrical voltages. Because there’s no electrical signal in the cable, external electromagnetic interference (EMI) or radio frequency interference (RFI) cannot couple into the data, so fiber remains immune to those disturbances. This is why fiber is favored in environments with lots of electrical noise or long-distance runs.

The other statements describe features of copper-based cabling rather than fiber. Wrapping each pair in metallic foil is a shield used with shielded copper cables, not a characteristic of fiber. The idea of combining cancellation, shielding, and twisting to protect data aligns with copper interference-reduction techniques, which fiber doesn’t rely on. And fiber cables aren’t described in terms of “4 pairs”; they use one or more individual fibers (or multi-fiber bundles), not copper-style pairs.