What link does Price Mechanism have with Perfectly Competitive Markets?

-PC Markets allow the Rationing, Signalling and Incentive Function work side by side -Firms being Price Takers infers that the Price is set by Consumer’s Preference. Resources are thus Rationed and Priorities are Signalled to Producers -Consumers having Perfect Knowledge and Producers being able to Enter/Exit the Market (Incentives to Intervene more or less?)