The diagram represents part of a polymer molecule. $-\text{CH}_2-\text{CH=CH}-\text{CH}_2-\text{CH}_2-\text{CH=CH}-\text{CH}_2-$ Which monomer would form this polymer?
- A$\text{CH}_2=\text{CH}_2$
- B$\text{CH}_2\text{CH}=\text{CH}_2$
- C$\text{CH}_3\text{CH}=\text{CHCH}_3$
- D$\text{CH}_2=\text{CH-CH}=\text{CH}_2$