[3 points] A transportation problem with m sources and n destinations will have decision variables and problem constraints when modeled as a linear programming problem. a. m+n,m+n b. mxn,m+n c. m+n,mn d. mxn,mxn [3 points] Which one of the following statements is true about "knapsack problems"? a. "Knapsack problems" are examples of minimization problems b. Variables in "knapsack problems" are allowed to have fractional values c. "Knapsack problems" generally have only one problem constraint d. All of the above statements are true about "knapsack problems