[xyxtem]

I'm sorry to bother you guys again. My teacher asked me to draw ALL possible sets of answers for the following question, but I still can't draw them all. Please help me.

Compound A (C₆H₆O₆) is an acyclic tribasic acid isolated from the leaves and tubers of Aconitum napellus. Hydration of A gives two isomeric compounds, B and D. B is achiral, but D is chiral. Deduce the structures of A, B and D.

All I drew were:
A:   HOOC       COOH
              C=C
            H      CH₂COOH

B:                COOH
   HOOC-CH₂-C-OH
                   CH₂COOH

D:  HOOC       COOH
       HO-C*-*C-H
           H       CH₂COOH

Please *delete me*

[xyxtem]

Please! Would somebody help???