Directing is a key managerial function that involves leading, motivating, communicating, and supervising employees to achieve organizational goals. It initiates action and ensures that employees work effectively toward organizational objectives. Option (A) is correct because directing is essential for translating plans into action. Option (B) is correct as directing brings harmony in group efforts by aligning individual efforts with the organization's overall goals. Option (C) is also true since effective direction helps an organization adapt to changes by guiding employees through transitions. However, Option (D) is incorrect because manpower estimation or workforce planning is a component of the staffing function, not directing. Staffing includes forecasting human resource needs, recruitment, and placement, whereas directing deals with instructing and guiding employees after they have been hired.
Final Answer: (D) Directing helps in estimating manpower requirements for the organization.