Currently an economy is producing (at a point on its production possibilities frontier) 100 units of good x and the opportunity cost of producing 1x is 3y. if good x is produced at increasing opportunity costs, then when the economy produces 120 units of good x (on the same ppf) the opportunity cost of producing 1y (not 1x) could be: (a) 1/4x. (b) 1/3x. (c) 1/2x. (d) 1x. (e) none of the above