The correct answer is D. Amount of the commodity offered for sale at a particular price per unit of time.
The supply of a commodity is the amount of that commodity that producers are willing and able to sell at various prices during a given period of time. The supply curve shows the relationship between the price of a good and the quantity supplied. The law of supply states that, all other things being equal, the higher the price of a good, the greater the quantity supplied. This is because producers are more willing to produce and sell a good when the price is high.
Option A is incorrect because it refers to the actual production of the commodity, not the amount that is offered for sale. Option B is incorrect because it refers to the total existing stock of the commodity, not the amount that is offered for sale. Option C is incorrect because it refers to the stock available for sale, not the amount that is offered for sale.