Answer:
A. you.
Step-by-step explanation:
The correct answer is A, because the actor that's responsible for choosing a healthcare provider is YOU, which means that every individual is the one that make this choice. Neither your doctor or nurse choose this. Even though, doctor, nurses or insurance companies would help you to choose by providing important information that fits with your needs, but the ultimate choice is made by the patient.
On the other hand, to make a good and wise decision, you should evaluate yourself and your health needs, maybe you need an internist to constantly check your body, or an cardiologist, because you have a specific heart condition. That's why this decision should be taken depending on the needs, not the publicity, or others opinion (at least is a professional opinion).