Which of the following influences the level of past, family, and social history?

a. The clinician's familiarity with the patient and the requirements for the specific E/M service visit
b. How thoroughly the patient can answer the questions
c. The level of the ROS
d. Whether the questions were asked by the performing physician or a supporting staff member

a) The clinician's familiarity with the patient and the requirements for the specific E/M service visit