Final answer:
In a perfectly competitive industry, established firms have no advantage over new firms. Identical products and free entry and exit in the market maintain balance and prevent dominance by any single firm.
Step-by-step explanation:
One requirement for an industry to be perfectly competitive is that established firms have no advantage over new firms. A key characteristic of perfect competition is that there are many firms producing identical products, which means there's no room for established firms to have an advantage over new entrants. The presence of many buyers and sellers, alongside the free entry and exit in the market, ensures that no single firm can influence the market price or gain an undue advantage over others.