Vertical communication refers to communication channels between hierarchical levels either in the downward or upward direction. Downward communication is the channel from top managerial levels to the rest of the organization. Upward communication follows a route from bottom to top, that is from employees to managers at any hierarchical level.Horizontal communication forms between positions and tasks at the same hierarchical level.Informal communication occurs outside the formal communication based on personal relations.The correct answer is C.