In enhanced shielded twisted-pairs (STP-A) cable, the _____ reduces low-frequency noise and provides immunity to other _____.

• A. Exterior shields
• B. Exterior braids
• C. Foil shields
• D. Outer jackets

Answer: (B)

Shielding with a braided exterior around the cable bundle is what gives STP-A its low-frequency noise reduction and helps prevent interference from neighboring cables. The exterior braid is a woven metal shield that sits around the conductors and is typically grounded. Because it provides a continuous, low-impedance path to ground, it shunts away low-frequency interference (like power hum) and reduces cross-talk from adjacent cables, giving the conductors better immunity to external noise.

Explanations for the other options: an exterior shield is a general term that could describe different shield types, but foil shielding—while excellent for high-frequency EMI—doesn’t offer the same effective low-frequency blocking as a braided shield. Outer jackets are just protective coverings and don’t provide shielding at all. So the braided exterior is the best choice for tackling low-frequency noise and shielding against interference from other cables.