Charlie conducted an experiment to show that magnetic force can only pass through non-magnetic materials. He held a bar magnet above a paper clip which was tied to a weight by a string. The magnet attracted the paper clip without touching it. He then placed four items, one at a time, between the magnet and the paper clip and observed if the paper clip dropped or remained where it was.

If the four items used in the experiment were a thin sheet of steel, a piece of aluminium foil, a piece of paper and a thin sheet of gold respectively, which one of the following observations would correctly show that magnetic force can only pass through a non-magnetic material?

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