Looking at the Production Function you will notice that Output increases at different rates to input added. First output increases at an increasing rate then at a constant rate then at a decreasing rate.
This shows the concept of the Law of Diminishing Marginal returns because as more input(labor) was added, at some point the output started increasing at a decreasing rate till it gets to a point where marginal returns will be negative.
The reason for this is that each worker is now working with less capital than before (assuming capital doe not change) and so will only produce less.
As the delegation is an assignment of the authority to carry out the specific activities. It is one of the core management concepts however the person remains accountable for the decision making and assignment of duty and the task.
Its an important factor that defines the success of the delegation is depended on the Individuals must be prepared for the delegation. The delegation can save time, money and motivate people.