Final answer:
The short-run supply curve for a purely competitive market is determined by the firm's marginal cost curve and shows the quantity of output that the firm is willing and able to produce at different prices in the short run.
Step-by-step explanation:
In a purely competitive market, the short-run supply curve for a firm is determined by its marginal cost curve. The short-run supply curve shows the quantity of output that a firm is willing and able to produce at different prices in the short run. The shape of the short-run supply curve depends on the firm's marginal cost curve and can vary from firm to firm.