George has $18 which he decides to spend on x and y. Commodity x costs $6 per unit and commodity y costs $9 per unit. He has the utility function U(x, y) = x + y and he can purchase fractional units of x and y. George will choose a. only y. b. some of each commodity but more x than y. < c. only x. d. some of each commodity but more y than x. J e. equal amounts of the two commodities.