X, Y and Z are three different hydrocarbons. $X\ \ \text{CH}_2{=}\text{CH}_2$ $Y\ \ \text{CH}_3{-}\text{CH}{=}\text{CH}_2$ $Z\ \ \text{CH}_3{-}\text{CH}_2{-}\text{CH}{=}\text{CH}_2$ Which feature do compounds X, Y and Z share?
- A1, 2 and 3
- B1 and 2 only
- C1 and 3 only
- D2 and 3 only