is A commodity that buyers and sellers both have will increase the efficiency of the market.

This is not an ideal scenario.

Explanation:

This is because sellers will only sell commodities that buyers are willing and able to buy. In this case, there will be market efficiency.

But in a scenario where a buyer and a seller both have a commodity, buying and selling will not take place, because the need for the buyer to purchase that commodity (which they already possess), from the seller will not exist. This will therefore lead to market inefficiency.

metallurgy is your answer

the "study of metals and the process of refining ("

note that it says metal. metallurgy has the word "metal" in it, and so is most likely your answer (and is your answer).

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