Which of the following can we learn from health care insurance?

Which of the following can we learn from health care insurance?
A、Different kinds of health care insurance cover expenses of different medical services.
B、All the health insurance policies cover regular visits to a doctor.
C、An insurer needn't pay for the medical services he/she has received.
D、Hospitals don't charge fees for meals and room in the hospitals.
【正确答案】：A