Some equilibria relevant to blood buffering are shown below: H2CO3 H3PO4 H* + HCO3 pK = 6.4 H- H,PO, pK, = 6.8 pK = 6.0-8.0 H. histidine Which statement is CORRECT? Select one alternative: O All deprotonated weak acids or bases are negatively charged. The wide pKa range of the histidine side chain means it cannot help to buffer the bloodstream to a healthy tight pH range At physiological pH 7 4 carbonic acid (H,CO,) and phosphoric acid (H,PO) are likely to dissociate to form their respective conjugate bases O The histidine side chain will always be found in its deprotonated form at physiological pH of -7.4.