Read the following passage about naval degaussing systems:
Naval degaussing systems counteract a ship's magnetic signature to prevent the detonation of magnetic influence sea mines. As a steel-hulled vessel moves through the Earth's magnetic field, its hull acquires permanent and induced magnetization. Degaussing installations consist of heavy electrical cables wrapped around interior compartments through which controlled direct current (DC) is passed. This current produces an opposing magnetic field that neutralizes the ship's overall magnetic field. Shipboard sensors continuously monitor local magnetic field variations and ship heading to automatically adjust coil currents. However, degaussing does not eliminate acoustic or thermal signatures, and it requires dedicated electrical power from shipboard generators rather than relying on natural hull dissipation.
Which factual assessment from the passage corresponds to each statement regarding the naval degaussing system?
- The degaussing coils utilize alternating current (AC) routed through exterior hull plating.Directly contradicted: the passage specifies that direct current (DC) is routed through interior compartment cables.
- The system counteracts permanent and induced magnetic fields to prevent mine detonation.Explicitly confirmed: the passage states this as the primary purpose of neutralizing the hull's magnetization.
- The operational process actively eliminates the vessel's acoustic and thermal signatures.Directly contradicted: the text explicitly states that the system does not eliminate acoustic or thermal signatures.
- Shipboard sensors monitor heading and magnetic variations to adjust coil currents automatically.Explicitly confirmed: the text notes that sensors track local field variations and heading for automatic adjustments.