=7. A linear program has been solved and sensitivity analysis has been performed. The ranges for the objective function coefficients have been found. For the profit on X1, the upper bound is 80, the lower bound is 60, and the current value is 75. Which of the following must be true if the profit on this variable is lowered to 70 and the optimal solution is found?

a. A new corner point will become optimal.

b. The maximum possible total profit may increase.

c. The values for all the decision variables will remain the same.

d. All of the above are possible.