Final answer:
For exchange in a competitive market, the essential condition is that sellers and buyers must agree on the price, as they should be informed about the product and its market conditions.
Step-by-step explanation:
In a competitive market governed by the principles of perfect competition, the essential condition for a good to be exchanged between a seller and a buyer is that they must agree on the price. This condition aligns with the concept that both buyers and sellers are well informed about products, including their prices and quality, to make rational decisions about their economic transactions. This information allows the market to reach equilibrium, where the quantity supplied equals the quantity demanded. Other factors like having the same preferences, equal bargaining power, or being in the same geographical location are not necessary conditions for exchange in a competitive market framework.
It is noteworthy that perfect competition assumes there are many sellers and buyers in the market, the products are identical, and there are no barriers to entry or exit from the market. Therefore, the correct answer in this context is that the seller and buyer must agree on the price for the exchange to occur.