Which of the following impacts all firms equally in a perfectly competitive market?

In a perfectly competitive market, all firms are price takers, meaning they accept the market price as given and cannot influence it through their individual actions. Market demand shifts affect all firms equally because these shifts lead to changes in the overall market supply and demand curve, thus impacting the equilibrium price that all firms must accept.

When there is an increase in market demand, for instance, the price level rises, creating an opportunity for all firms to sell their product at this higher price. Conversely, if there is a decrease in market demand, the price level falls, and all firms experience this reduction in revenue.

In this context, unlike factors such as government regulations, which might affect certain firms differently based on their size or operations, or pricing strategies, which are unique to individual firms and how they compete, market demand is a fundamental aspect of the market as a whole. Therefore, the impact of market demand shifts is uniformly felt across all firms in a perfectly competitive environment.