Acid-base balance?

Question

Homeostatically, in order to help maintain acid-base balance, the kidney

a. retains hydrogen ions

b. retains carbon dioxide

c. retains bicarbonate ions

d. excretes bicarbonate ions

is it d or maybe c?? Not b for sure. Help!

Answer 1

I would guess d out of d and c, because bicarb is basic and so is urine (as far as I can remember), so it would make sense that they would be excreted. Could be wrong, though.