Amanda, the CEO of a company, knows that constructive conflict can help bring problems to the forefront and develop innovative solutions for them. When she faced the conflict of whether or not to merge with a rival company, she brought the issue to the notice of a select group of employees and encouraged them to discuss the advantages and disadvantages of the merger. She assigned Steve, the vice president of the company, the task of challenging each and every assumption and assertion made by the group. In the given scenario, Steve played the role of a _____.