I want to make a database that holds information about a small medical practice. Here is a description of the real world situation $($this is a vastly oversimplified situation$)$

This medical practice is named Alice$$s Health Care.

Patients are registered with the practice.

The practice maintains the following patient information: name, social security number, birthdate, phone number, patientID number, and address.

The patientID number is a number the practice uses to identify a patient so that social security numbers can remain private.

Patients have insurance.

Insurance companies have a name, address, and phone number, and that is all

The practice has $5$ doctors. We need to record the doctor$$s name and employeeID number.

A patient is assigned to exactly one doctor

When a patient has a doctors visit, we record the patient, their assigned doctor, the doctor they actually saw $($the assigned doctor might not be available$),$ and the insurance company the patient used for this visit.

Question:

Is the Assigned Doctor relationship $1$ to $1,$ many to $1,$ or many to many $($it might be useful to draw your own ER diagram of the situation$)?$