For a Weak Diprotic Acid, H₂A, for Which K_a1 =

For a weak diprotic acid, H₂A, for which K_a1 = 2.1 x 10^-7 and
K_a2 = 4.3 x 10^-13 the A^2- ion concentration at equilibrium will be:

A) approximately equal to the initial concentration of H₂A.
B) roughly equal to K_a2.
C) roughly equal to the HA^- concentration.
D) much larger than the HA^- concentration.
E) approximately equal to the H₃O⁺ concentration.