The function refers to-

The correct answer is D.

A function is a mathematical relationship between one dependent variable and one or more independent variables. In economics, the demand for a commodity is a function of the price of the commodity, the income of consumers, the prices of other commodities, and consumer tastes. The supply of a commodity is a function of the price of the commodity, the cost of production, the technology used in production, and the prices of other inputs. The demand and supply of a commodity together determine the equilibrium price and quantity of the commodity.

Option A is incorrect because the demand for a commodity is only one of the factors that determines the price of a commodity. The other factors are the supply of the commodity, the cost of production, the technology used in production, and the prices of other inputs.

Option B is incorrect because the supply of a commodity is only one of the factors that determines the price of a commodity. The other factors are the demand for the commodity, the cost of production, the technology used in production, and the prices of other inputs.

Option C is incorrect because the demand and supply of a commodity are two different things. The demand for a commodity is a function of the price of the commodity, the income of consumers, the prices of other commodities, and consumer tastes. The supply of a commodity is a function of the price of the commodity, the cost of production, the technology used in production, and the prices of other inputs.