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