When answering this question, you should take both structural isomerism and stereoisomerism into account. How many isomeric compounds with molecular formula $\text{C}_5\text{H}_6\text{O}_4$ have two $-\text{CO}_2\text{H}$ groups and a single $\text{C=C}$ double bond?
- A5
- B6
- C7
- D8