Of the following pairs of acids and conjugate bases, which should be used to prepare a buffer solution whose pH is approximately 5.0?

Boric acid (Ka = 5 x 10-5) and sodium borate


Acetic acid (Ka = 1.8 x 10-5) and sodium acetate


Sodium hydrogen sulfate (Ka = 1.2 x 10-2) and sodium sulfate


Phosphoric acid (Ka1 = 7.1 x 10-3) and sodium dihydrogen phosphate


Carbonic acid (Ka1 = 3.5 x 10-7) and sodium bicarbonate