Answer:
I, II, and IV only
Step-by-step explanation:
A perfectly competitive industry is an industry in which all firms sell an homogeneous product, all firms are price takers, buyers have complete about the product being sold and the prices charged by each firm.
Moreover, Firms can enter or exit the market without cost.
A perfectly competitive industry exists if the product sold is similar across firms, there are many sellers, each small relative to the total market and the threat of competition exists from potential sellers that have not yet entered the market.
So, answer is option d) I, II, and IV only