For which of the following equilibria does Kc correspond to the acid-ionization constant, Ka, of H2CO3?

For which of the following equilibria does Kc correspond to the acid-ionization constant, Ka, of H2CO3?

a.

H2CO3-(aq)+2OH-(aq) ⇌CO32-(aq)+2H2O(l)

b.

H2CO3(aq) + H2O(l) ⇌HCO3-(aq) + H3O+(aq)

c.

HCO3-(aq) + H2O(l) ⇌H2CO3(aq) + OH-(aq)

d.

H2CO3(aq) + H3O+(aq) ⇌HCO3−(aq) + H2O(l)

e.

HCO3-(aq) + H2O(l)⇌ CO32-(aq) + H3O+(aq)