The most expensive management function for a nonprofit organization is ______.

A) planning
B) marketing
C) research and development
D) human resources management

Human resources management is the most expensive management function for a nonprofit organization as it involves hiring, training, and compensating employees. Nonprofits often rely heavily on staff to carry out their mission, making human resources management crucial but costly. Planning, marketing, and research and development are also important functions, but they typically do not require as much financial investment as human resources management.