The correct answer is C. Decision-making.
Staffing is the process of finding, hiring, and training employees. It includes activities such as job analysis, recruitment, selection, orientation, and training. Decision-making is not directly related to staffing, as it is a more general process that can be applied to any area of business.
Human resource planning is the process of ensuring that an organization has the right number of employees with the right skills and abilities to meet its current and future needs. Managerial appraisal is the process of evaluating the performance of managers. Job definition is the process of describing the duties and responsibilities of a job.
All of these activities are important for staffing, but decision-making is not specifically related to staffing.
