Suppose the demand function for good X is given by: a = 15-0.5P, -0.8P, where is the quantity demanded of good X, P, is the price of good X, and P, is the price of good Y, which is related to good X Refer to Scenario 5-2. Using the midpoint method, if the price of good X is constant at $10 and the price of good Y decreases from $10 to $8, the cross price elasticity of demand is about O

a.-0.80, and X and Y are complements
b.-2.57, and X and Y are complements.
C.-0.22, and X and Y are complements.
d. 0.57, and X and Y are substitutes.