In long-run competitive equilibrium SRATC = LRATC, because if SRATC > LRATC (at the quantity of output at which MR = MC) firms would have an incentive to change their plant size to produce their current output.
Option: A
Explanation:
In perfect competition, balance is the stage where consumer demands are equal to market supply. In the short term demand can impact stability. In the long run both a product's demand and supply would influence the balance in perfect competition.
The increase in the quantity of output generated is the SRTC i.e short-run total cost and LRTC i.e long-run total cost scales because generating more output needs more labor utilization for both the short and long runs, and since, in the long run, generating more output implies using more of the physical resource supply; and by using more of either supply means incurring more production costs.
