Final answer:
John's job dissatisfaction is most likely due to C. Poor working relationships with his boss, which is essential for job satisfaction and influences career growth and personal development.
Step-by-step explanation:
In the scenario where John, an executive at a top investment firm, frequently engages in heated debates with his boss due to differences in project execution views and conflicting working styles, John is most likely to be dissatisfied with his job because of C. Poor working relationships.
A healthy working relationship with a supervisor is critical for job satisfaction. The fact that neither party seems able to reach a consensus may lead to continuous frustration, a negative working environment, and a strained relationship which, if unresolved, could result in the diminishing of John's job satisfaction. Given that this discord is occurring with his manager, who wields considerable influence over job satisfaction, personal growth, and career advancement opportunities, John's dissatisfaction is rooted in the quality of professional relations he maintains with his supervisor.