Which statements about shielded wiring are correct?

• A. A only
• B. Neither
• C. B only
• D. Both A and B

Answer: (D)

Shielded wiring uses a conductive shield around the conductors to intercept external electromagnetic interference and carry that noise to ground, keeping the actual signal clean. In a vehicle environment, this helps protect sensor and control lines from interference caused by ignition systems, motors, and power electronics, preserving accurate voltage levels and reducing crosstalk.

A key point is that the shield must be continuous and properly terminated to ground so it can do its job. Grounding the shield provides an effective return path for the intercepted noise, but the grounding approach matters to avoid creating ground loops that could introduce additional noise. When both of these ideas are true—that shielding blocks interference and that the shield is correctly grounded—the statements about shielded wiring are both correct, which is why the best choice is that both are true.