Concept:The supply of land refers to the total surface area of the earth that is available for human use.Explanation:The total quantity of land on earth is limited and cannot be increased or decreased by any human action.From the viewpoint of society as a whole, this supply is fixed and does not change over time.Although the use of land for a particular purpose can change, the aggregate supply of land remains constant.Thus, land is said to have a perfectly inelastic supply.Answer:D. is fixed