Describe each of the three levels of care, with a focus on the following:  How do they relate to each other?  How do they differ in terms of both cost and in terms of the number of people who in general are in need of each level of care? B) Give some examples of the statement, “Common disorders commonly occur and rare ones rarely happen.” What are the implications of this statement for the need for larger numbers of primary care providers versus tertiary care providers?