Which of These Statements Is Best

Multiple Choice

Which of these statements is best?

A) If all of a resource represented by a slack variable is used, that slack variable will not be in the production mix column of a linear programming simplex tableau.
B) In linear programs with many variables, even though we cannot graph the feasible region, the optimal solution will still lie at an interior point.
C) A surplus variable is added to a constraint in order to create an equality, and represents a quantity of unused resource.
D) If there are seven less-than-or-equal constraints in a problem, the simplex table contains seven surplus variables.