The argument is claiming that it is natural that beads were once used as currency. This is because other objects (gold, silver, feathers) that were once used as currency were "first used...as decorative objects." Thus, it makes sense that beads, which "were initially valued as objects of adornment" would come to be used as currency.
Answer choice C is correct because it points out the pattern we see in the argument - objects that share the same initial use (in this case, decoration/adornment) will likely all share the same second use (currency).
Answer choice E is incorrect; it states "the more an object is used to represent value in general, the more likely it is to be valued for particular uses." This is different from the argument (in fact, it almost reverses it in a way). The argument makes the point that the more an object is valued for a particular use (adornment/decoration), the more natural it is for that object to be used to represent value in general (as currency). Choice E does not help to justify this point and is thus incorrect.
I hope this helps to clarify. Please let us know if you have any additional questions!