Final answer:
Gold coins were the most valuable in the Fatimid period due to their rarity and association with power and wealth(option a).
Step-by-step explanation:
In the Fatimid period, the most valuable coins were gold coins. There are a few reasons for this. First, gold coins were valuable due to their scarcity(option a).
Gold is a precious metal that is relatively rare, so the limited supply made these coins highly sought after. Additionally, gold coins were often used as diplomatic gifts and treasury items, further increasing their value. Finally, gold coins were a symbol of power and wealth, and they were often associated with rulers and monarchs.