The Labour Contract for Union Employees at Caterpillar Has Expired

The labour contract for union employees at Caterpillar has expired, and the negotiators have been unable to come up with a new contract. While negotiations continue, the workers have agreed to continue working without a contract. Which of the following is another option to consider in this situation?

A) the union files a lawsuit against the company
B) both union and management replace their current negotiators with new representatives
C) the union goes on strike
D) management threatens to fire union employees to force them to agree to their terms