Structural isomerism and stereoisomerism must be taken into account when answering this question. Which formula identifies only one substance?
- A$\text{CH}_3\text{CHClCH}_2\text{CHO}$
- B$\text{CH}_3\text{CHCHCH}_3$
- C$\text{CH}_2\text{ClCH}_2\text{CHCl}_2$
- D$\text{C}_4\text{H}_{10}$