The modeling phase is the transformation of verbal description of the problem into a mathematical model under the linear programming assumptions. This model is a system of equations and inequalities representing the objective and the constraints. The decision to be derived from the model is related to quantifiable variables that are in control. These variables of decision x₁, x₂, ... , x_n and the constants (i.e. the coefficients and right-hand side values of the inequalities) are called the decision variables and the parameters respectively. The objective function (for example, Z= 2x₁ + x₂) is an appropriate measure of performance for the problem. It can be maximized or minimized depending on the desired achievement. Finally, a constraint is a restriction on decision variables by means of equality or inequality (for example, 5x₁ + 6x₂ ? 30). As also understood from the information given, the statements in the options I, II and III are correct, so the correct answer is C. The statements in the option IV and V are not correct because of the fact that These variables of decision x₁, x₂, ... , x_n and the constants (i.e. the coefficients and right-hand side values of the inequalities) are called the decision variables and the parameters respectively.