Certain ethnic communities incorporate beliefs about the causes and cures of diseases that would be regarded as supernatural or superstitious by traditional medicine. this is characteristic of

Lay referral networks

Explanation:

 According to the question, the lay referral network is basically consist of different types of ethnic communities that involve family, friends and the other social relationship that incorporating the beliefs about the cures and the causes of the specific diseases. It is regarded in the form of supernatural by the traditional medicine.

It influenced the individual people about the symptoms and the different types of health threats. It also improving the symptoms management. It also helps in improving the symptoms management.  

 Therefore, Lay referral is the correct answer.

i think it's b or c hope this