$Z$ is a compound made from sodium, chlorine and oxygen. It has $45.1\%$ oxygen by mass. $Z$ is made by reacting sodium hydroxide with chlorine. Which row gives the reaction conditions and the oxidation state of chlorine in $Z$?
- Acold dilute $\text{NaOH}$, $+1$
- Bcold dilute $\text{NaOH}$, $+5$
- Chot concentrated $\text{NaOH}$, $+1$
- Dhot concentrated $\text{NaOH}$, $+5$