Final answer:
Mark is using projection, a defense mechanism where he projects his own feelings of job dissatisfaction onto his colleagues instead of acknowledging his own emotions.
Step-by-step explanation:
Mark is using projection when he attributes his dislike for his job onto his colleagues, instead of acknowledging his own negative feelings. This defense mechanism involves projecting one's own unwanted emotions or traits onto another person. For example, Mark's suggestion to his colleagues that they are unhappy could be his way of deflecting attention from his own feelings of discontent. Instead of confronting his work dissatisfaction, he implies that it is his colleagues who dislike their jobs. This is a common psychological response to cope with unpleasant emotions or thoughts.