When a new position in her collective bargaining unit opened up, Karen thought she would be selected because she had the experience outlined in the job posting. However, the position went to someone who had more seniority but whose skills didn't align as well with the job requirements. Karen thought this was unfair. What is the first thing Karen should do to ensure the contract was enforced correctly?
a) go on strike
b) arrange a decertification process
c) ask an arbitrator to review the decision
d) file a grievance