The right answer is B. Gold and Silver.
Context: Specie Circular was a presidential executive order of President Jackson, which specifically demanded that goverment be paid for land in gold and silver. It was felt at the time that banknotes and other similar currency were not reliable enough and that its value could fluctuate. In contrast, gold and silver have a relatively stable value - specially when compared with the so-callled soft currency, which can be influenced by speculation.
