What is the most suitable word that describes the work of a policeman according to the passage

A．getting the most work done
B．dividing the work up systematically
C．each ant helping with all the tasks
D．each ant doing what it can do best

A．He has to get the most desirable results without breaking the law in any way.
B．He has to justify his arrests while unable to provide sufficient evidence in most cases.
C．He can hardly find enough time to learn criminal law while burdened with numerous criminal cases.
D．He has to provide the best possible public service at the least possible expense.