Find the values $X \mathrm{and} Y$  in the given factor tree.

Given:

The factor tree of $18$.

$X$ will be the smallest factor of $18$, that is $2$.

So, the factor tree will be:

Now, $Y$ will be the smallest factor of $9$, that is $3$.

So, the factor tree of $18$ will be:

Therefore $X = 2 and Y = 3$.

Hence, option C is correct.