Solution:In Perfect Competition, the correct statements about a firm's equilibrium are.The market price must be greater than or equal to Average Variable Cost (AVC) in the short run.
If the price falls below AVC, the firm would shut down in the short run. The market price must be equal to Marginal Cost (MC) at equilibrium. This ensures that the firm is maximising profit or minimising loss.
The market price must be equal to Average Cost (AC) in the long run. This is because, in the long run, firms enter or exit the market until economic profits are zero.
The Marginal Cost (MC) does not necessarily decrease at the equilibrium output. The MC curve can be upward sloping and the firm reaches equilibrium where MC equals the market price, which does not imply that MC is decreasing at that output.