Assume there is a decrease in the market demand for a good sold by price-taking firms that are initially producing the profit-maximizing level of output. How will the market adjust over time? Firms will exit the market, causing price to fall until positive profits are eliminated. Firms will exit the market, causing price to rise until losses are eliminated. Firms will enter the market, causing price to rise until losses are eliminated. Firms will enter the market, causing price to fall until positive profits are eliminated.

Answer: Firms will exit the market, causing price to rise until losses are eliminated

Explanation:

When there is a decrease in demand in a Perfectly Competitive Market, firms will have to start producing at a lower Quantity to manage their Marginal cost. This leads to Economic losses on their part in the short run.

In the long run however, should the situation remain the same, the new price would be less than their Average Cost which would deepen Economic losses. Firms would respond by exiting the market in the long run.

As the firms exit, the supply curve shifts left as supply drops. This drop in supply leads to a price rise. The exits will continue until enough firms leave that the market's remaining firms will stop suffering economic losses.