The MOST important feature of the material used for making the binnacle of a standard magnetic compass is that it is __________.

Correct Answer: Option D — nonmagnetic

A binnacle must be constructed of nonmagnetic materials, such as brass or specialized alloys, to prevent interference with the magnetic compass. Any magnetic material would induce deviation, rendering the compass unreliable for steering and navigation, which violates the fundamental requirements for shipboard magnetic compass installations under 46 CFR.