Answer:
all firms produce and sell a standardized or undifferentiated product
Step-by-step explanation:
A perfectly competitive market is a market in which there are many companies that offer the same product, there are not entry barriers which makes it easy for an organization to enter or exit the market. Also, the companies are not able to influence the market and they are not able to control the conditions in it. According to this, the answer is that in a perfectly competitive market, all firms produce and sell a standardized or undifferentiated product.