Which ancient civilization pioneered the use of 'ostraka' (pottery fragments) as an early customer feedback system in marketplaces?

Before modern retail analytics and customer surveys, ancient civilizations had their own methods of gathering customer feedback and improving their marketplaces. The bazaars and agoras of the ancient world were sophisticated commercial centers where merchants developed surprising techniques to understand consumer preferences and build loyalty. Test your knowledge about these early customer feedback systems!

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Ancient Egyptians, who collected marked pottery shards indicating preferred goods at temple marketplaces
Ancient Greeks, who used ostraka primarily for voting but adapted the practice for merchant stalls in the agora
Mesopotamians, who developed the first written customer complaint system on clay tablets for the royal markets
Roman merchants, who initiated the 'testae mercatus' system where patrons marked preferences on amphora fragments