In the addition polymerisation of alkenes, which bonds are broken and which bonds are formed?
- A$\pi$ only broken, $\sigma$ only formed
- B$\pi$ only broken, $\sigma$ and $\pi$ formed
- C$\sigma$ and $\pi$ broken, $\sigma$ only formed
- D$\sigma$ and $\pi$ broken, $\sigma$ and $\pi$ formed