AI Generated Response: For perfectly competitive marketsor, more generally, for markets in which individual sellers can sell whatever quantity they wish at a constant pricethe seller's best option is to sell that quantity of output for which price equals marginal cost, provided price exceeds the minimum value of average variable cost. The supply curve for the seller thus coincides with the portion of his marginal cost curve that exceeds average variable cost. This is why we sometimes say the supply curve represents the cost side of the market (in contrast to the demand curve, which represents the benefit side of the market). How would you say taxes affect this? In 50 words describe how taxes can affect the seller's best option