What Is the Causal Pathway by Which Physicians Per 1,000

What is the causal pathway by which physicians per 1,000 persons may affect health care quality?:

A) Access to medical care can take longer if the physicians per 1,000 is too low
B) The panel size may be too long
C) Large panel sizes may, according to Dahrouge et al., lead to decreases in quality
D) All of the above
E) None of the above