Which communication medium provides EMI protection through shielding?

• A. Two-wire
• B. Shielded
• C. Ethernet
• D. Plenum

Answer: (B)

Shielding around the conductors creates a conductive barrier that intercepts external electromagnetic fields and provides a path to ground, so interference is kept out of the signal and the cable’s emissions are suppressed. This is what a shielded communication medium does—wraps the wires in metal foil or braid to block EMI. The other options lack this protective barrier: a simple two-wire run has no shielding; plenum refers to the cable’s installation rating (not protection from EMI); Ethernet can be either shielded or unshielded, but the term shielded specifically denotes the presence of shielding. For environments with significant interference, using a shielded medium helps maintain signal integrity by reducing both susceptibility to EMI and unintended radiation.