please give me the answer of 30 and 31

30. The property of linear programming models indicates that the decision variables will not be restricted to integer values and therefore, can take on any fractional value. A) linearity B) additive C) divisibility D) certainty E) proportionality 31. The condition of infeasibility occurs when a one of the decision variables is negative at the optimal solution b. there are one or more constraints which do not affect the solution c. there is no solution that satisfies all the constraints. d. the objective value can be made infinitely large without violating any of the problem's constraints