Which of the following is correct

1, Hydrogen ions are secreted by Na+/H+ antiporters in the proximal tubules

2,H+ATPases (proton pumps) in the collecting secrete hydrogen ions

3,Cl-/HCO3- antiporters help with hydrogen ion reabsorption

     a,1 only

      b, 2 only

      c, 3 only

       d, 1 and 2 are correct

        e, 1,2, and 3 are correct

Metabolic reaction can produce

a, H+

b, HCO3-

c, Nonvolatile acids

d, Volatile bases

E, Ca+1