Which of the Following Business Rules Illustrates a Proper Implementation

Which of the following business rules illustrates a proper implementation of internal control?
A. The employee that inspects the work can't be the same employee that discards defective items.
B. The employee that performs part of the conversion work can't also perform other work in the conversion process.
C. The employee that authorizes production can't be the same employee that issues raw materials.
D. The person that receives the finished items can't also place them into their assigned warehouse location.