下列化学反应在理论上可设计成原电池是

A．2Al(s) + 2NaOH(aq) +2H2O(l) ="=" 2NaAlO2(aq) + 3H2(g) △H<0

B．HNO3(aq) + KOH(aq) ="=" KNO3(aq) + H2O(l) △H<0

C．Ba(OH)2·8H2O(s) + 2NH4Cl(s) ="=" BaCl2(aq)+ 2NH3·H2O(aq)+ 8H2O(l) △H﹥0

D．Na2O(s)+ H2O(l) ="=" 2NaOH(aq) △H<0