An astatine nucleus has a nucleon number of $218$ and a proton number of $85$. It undergoes decay to make a polonium nucleus, with a $\beta$-particle and an $\alpha$-particle emitted during the process. What are the nucleon number and the proton number of this polonium nucleus?
- Anucleon number $214$, proton number $83$
- Bnucleon number $214$, proton number $84$
- Cnucleon number $215$, proton number $83$
- Dnucleon number $216$, proton number $82$