A line manager's human resource responsibilities most likely exclude which of the following?

The responsibilities of a line manager typically focus on managing their team, which includes tasks related to human resources such as maintaining department morale, controlling labor costs, and protecting employees' health. These responsibilities align closely with the effective management and well-being of team members, which is a hallmark of a line manager's role.

On the other hand, marketing new products and services falls outside the purview of human resource responsibilities. This task is primarily related to a marketing or sales function within an organization, focusing on promoting products and services to customers rather than managing employee-related issues or taking care of team dynamics. Thus, focusing on the operational aspects of the team rather than external marketing efforts makes option D the most appropriate exclusion from a line manager's core human resource responsibilities.