In the USA is is the law. Medical issues are private matters between a healthcare provider and patient. If a person's private information was to "get out" it might affect their ability to get a job or they might face other predjudices Also the private insurance numbers could be used to steal someone's identity.
It depends on the type of drug you mean, such as medicinal drugs like marijuana, or bad drugs like cocaine or heroine. But the best answer(in my opinion) is B.
