critical processes in IT management and governance

I come across an article on IT Governance. It said there are 6 core processes in IT management and governance, namely :

1. Demand Management
2. Portfolio Management
3. Project and Program Management
4. Resource Management
5. Financial Management
6. Asset Management

All of these processes are focused on providing visibility, control, and utilization of IT resources to maximize business value.

For my curiosity, which one of the above 6 processes is the most difficult one to manage ? The answer is .....