18 Suppose we have obtained the tableau in Table 75 for a maximization problem. State conditions on a1, 22, 23, b, C1, and c2 that are required to make the following statements true: I a The current solution is optimal, and there are alter- native optimal solutions. b The current basic solution is not a basic feasible solution. TABLE 75 z X1 X2 X3 X4 Xg rhs 1 C2 0 0 C1 4 -1 0 0 0 0 0 ai d2 -1 0 0 0 1 10 b 2 3 0 -5 -3 03 0 0 -4