Effective supply is the total amount of a commodity

Step 1: Analyze the question The question asks for the meaning of "effective supply" in Economics.

Step 2: Explain the concept In economics, supply can be viewed in different ways:

• Stock: the total quantity of a commodity that exists (for example, in warehouses).
• Market supply: the total of all producers' output.
• Effective supply: the quantity that sellers actually bring to the market and offer for sale at a given price. It is the supply that really reaches buyers, as opposed to goods merely held in stock or produced but not offered.

Step 3: Evaluate each option

• A. From a single producer. This describes individual supply, not effective supply.
• B. In the warehouse of producers. This describes stock, which is not offered for sale.
• C. Offered for sale at a market place. This matches the definition. Effective supply is the quantity actually put up for sale in the market.
• D. Produced for the market. This is the total output. Not everything produced is necessarily offered for sale, since some may be held back in stock.

Step 4: Answer

Tip: Link the words effective and actual. Effective supply is the amount actually on offer in the market, just as effective demand is demand backed by the ability to pay. Whenever you see "effective," think "real and actually in action."