Concept:Perfect competition is a market structure where no single buyer or seller can control the market price, and all participants have full access to relevant market information.
Explanation:One essential feature of perfect competition is that buyers and sellers possess adequate knowledge of existing prices.
This means every firm knows the going market price, and every consumer knows the prices charged by different sellers.
With perfect information, no firm can charge a higher price, and no buyer will pay more than the market rate.
Because of this, each firm becomes a price taker rather than a price maker.
Option B is wrong because individual economic units cannot influence prices in perfect competition.
Option C is wrong because there is free movement of goods and services with no restrictions.
Option D is wrong because prices are determined by market forces of demand and supply, not by a centralized authority.
Therefore, the feature listed among the options that matches perfect competition is adequate knowledge of existing prices.
Answer:A. Adequate knowledge of existing prices