Supply is best defined as b – the amount of a good that producers are willing and able to sell at each possible price, other things constant. This definition captures the essential relationship between the price of a good and the quantity supplied by producers.
To elaborate, supply reflects how much of a product is available in the market at various price points. When prices rise, producers are generally more inclined to increase production to take advantage of higher potential profits, leading to a larger quantity supplied. Conversely, if prices fall, the incentive to produce decreases, resulting in a lower quantity supplied. Hence, the law of supply suggests a direct relationship between price and quantity supplied, making option b the correct choice. Options a and c do not adequately capture this relationship or the crucial role of price in supply.