Why Is It Important to Know How Many People Have

Why is it important to know how many people have diagnosable mental illnesses?

A) If the incidence of mental illness is rising there needs to be a corresponding increase in the level of funding for medical research.
B) Pharmaceutical companies need such information to ensure the appropriate level of drug production.
C) Such information is needed to plan for the provision of adequate services.
D) The number of people with mental illness and the level of crime are highly correlated.