Using the Above Table,fill in the Blank with the Appropriate

Using the above table,fill in the blank with the appropriate integer (1 ,2,3,...) indicating the buffer and/or the letter indicating the formula below.
-In Buffer 2,_________________________ would react with added acid.

A) H₃C₂O₄⁺
B) HC₂O₄^-
C) C₃H₄O₃^2-
D) HC₃H₅O₃
E) C₂H₃O₂^-
F) H₂C₂H₃O₂
G) C₃H₅O₃^-