Question: The diagram above represents the idealized titration curve for the reaction of sodium oxalate ($Na_2C_2O_4$) with a strong acid like hydrochloric acid ($HCl$). E and F represent the pH at the endpoints. G and H will depend on the composition of the sample with the possibility that one may not be present. In addition to water, what are the predominant species in solution at E? A) $Na_2C_2O_4$ and $HCl$  B) $Na^+$, $Cl^-$, and $HC_2O_4^-$  C) C_2O_4^{2-} and $H^+$  D) $Na^+$, $H^+$, and $C_2O_4^{2-}$. Please choose an answer from [A, B, C, D].
Answer: B