David Is a Nursing Student on Placement at a Seniors

David is a nursing student on placement at a seniors' home.He has worked with two different doctors and one doctor is much more effective at getting the patients to be very open and disclose a lot of information as opposed to the other doctor.Which reason best explains why one doctor is more effective?

A) The doctor spends a lot of time with his patients.
B) The doctor explains things well to his patients.
C) The doctor uses a lot of direct eye contact with the patients.
D) The doctor is friendly and makes small talk with the patients.