Will the force of attraction by a magnet of an iron nail change: a) if, without changing their relative position

Will the force of attraction by a magnet of an iron nail change:
a) if, without changing their relative position, the nail is placed in a box made of glass;
b) if you put a nail in a cardboard box;
c) if you immerse a magnet and a nail in water?

A) will not change B) will not change C) will not change.

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