An economy can produce either of these two combinations of goods X and Y: 1,000X and OY or 400Y and OX. Furthermore, the opportunity cost between the two goods is always constant. Which of the following combinations of the two goods, X and Y, is it possible for the economy to produce? a. 100 units of X and 600 units of Y b. 700 units of X and 280 units of Y c. 300 units of X and 280 units of Y d. 400 units of X and 150 units of Y e. 600 units of X and 250 units of Y