Quiz 03: Applying Consumer Theory (Ch. 5) Question 01 Ethan's preferences over goods X and Z can be represented by the utility function = As such, his optimal demands are = Y/2px and T Y/2pz. Prices are px = pz = $5 and his income is Y = $120. The picture below shows how Ethan changes his optimal consumption bundle when the price of good Z increases first to pz ' thentop; = $15. The green "curve" in the figure represents Ethan's: (a) Engel curve (b) demand curve for good Z (c) indifference curve (d) price-consumption curve