Final answer:
Gold coins and banknotes backed by gold are forms of commodity-backed currencies, while silver certificates and cryptocurrency are examples of fiat money.
Step-by-step explanation:
Gold coins and banknotes backed by gold are forms of commodity-backed currencies, as they both have their value tied to gold. However, silver certificates and cryptocurrency fall under the category of fiat money.
Fiat money is inconvertible paper money that is made legal tender by a government decree and is not backed by a physical commodity like gold or silver. It gains its value solely because the government declares it to be legal tender.
Therefore, option 2 (Silver certificates) and option 3 (Cryptocurrency) are the answers that apply to fiat money and not representative currency.