What Effect Would a Decrease in the Na+ Concentration of Filtrate

Multiple Choice

What effect would a decrease in the Na+ concentration of filtrate have on the pH of tubular fluid?

A) pH would increase because more hydrogen ions could be secreted by countertransport.
B) pH would decrease because more hydrogen ions could be secreted by countertransport.
C) pH would increase because fewer hydrogen ions could be secreted by countertransport.
D) pH would decrease because fewer hydrogen ions could be secreted by countertransport.
E) pH would not be affected because hydrogen ions are countertransported with K+ not Na+.