There Are Guidelines for Effective Delegating

There are guidelines for effective delegating. Which of the following is not one of them?

A) Avoid the mistake of delegating the job without also spelling out in detail the approach that should be taken to do the job the way you want it done.
B) Have an idea ahead of time about what capacities each subordinate has.
C) Make each assignment within the reach, or perhaps just slightly above the reach, of the subordinate receiving the assignment.
D) Be prepared to accept occasional mistakes by subordinates.