A manufacturer has three plants with access production capacity. It can use this capacity to produce a product that comes in three sizes, Large, Medium, and Small. Any plant can produce any combination of the product sizes. The manufacturer wants to determine how many units to produce in each plant of each product size. The decision variables to solove for are therefore: Plant 1 Plant2 Plants Large X11 Medium X21 Small X31 X12 X22 X32 X13 X23 X33 1. The forecast of sales for each product size is known to be 900, 1200, 750 units for the Large, Medium and Small products respectively, so production levels should not exceed these values. Which option describe these conditions properly? a. X11+X12+X13+X21+....+X33= 900; X21+X22+X32 >= 1200; X31+X32+X33 >= 750 d. None of the above 2. There is a limited storage available in each plant, which limits the production levels. The storage space available in each plant, and the required space per unit are given (below question 4). Write the constraints that express the limited space available for each plant. (in the Answers sheet). 3. Note the limited production capacity in each plant, given below. For example, Plant 1 cannot produce more than 1200 units. Which constraints describe this situation? a. Plant 1