The demand for good X is estimated to be Qxd = 10,000 - 4PX + 5PY + 2M + AX, where PX is the price of X, PY is the price of good Y, M is income, and AX is the amount of advertising on X. Suppose the present price of good X is $100, PY = $50, M = $25,000, and AX = 1,000 units. Based on this information, we know that the demand for good X is a. elastic b. inelastic c. unitary elastic d. neither elastic, inelastic, nor unitary elastic.