Ethanol may be transformed into propanenitrile in two stages. $\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{X} \text{CH}_3\text{CH}_2\text{Br} \xrightarrow{Y} \text{CH}_3\text{CH}_2\text{CN}$. What types of reaction are $X$ and $Y$?
- Afree-radical substitution; electrophilic substitution
- Bfree-radical substitution; nucleophilic substitution
- Cnucleophilic substitution; nucleophilic substitution
- Dnucleophilic substitution; electrophilic substitution