Final answer:
A head of a marketing department is least likely to be a first line manager, as they are usually part of the middle or upper management, responsible for overseeing a functional area and supervising other managers or team leaders.
Step-by-step explanation:
The individual least likely to be a first line manager is C. a head of a marketing department. First line managers are typically at the lowest level of management within an organization, and they manage the work of non-managerial employees who are directly involved with the production or creation of the organization's products. A head of a marketing department is more likely to be part of the middle or upper management, as they oversee a significant functional area of a company and usually have managers or team leaders reporting to them.