Consider the following reactions:
$Cs + O_2 \text{ (excess)} \rightarrow X$
$Na + O_2 \rightarrow Y$
Identify the correct statement about $X$ and $Y$.

• A
  $Y$ is monoxide and $X$ is superoxide
• B
  $Y$ is peroxide and $X$ is peroxide
• C
  $Y$ is peroxide and $X$ is superoxide
• D
  $Y$ is superoxide and $X$ is peroxide