d
Given, $D=\left|\begin{array}{ccc}{1} & {1} & {1} \\ {1} & {1+x} & {1} \\ {1} & {1} & {1+y}\end{array}\right|$
Apply $\quad R^{2} \rightarrow R_{2}-R_{1}$
and $\quad R \rightarrow R_{3}-R_{1}$
$\because \quad D=\left|\begin{array}{lll}{1} & {1} & {1} \\ {0} & {x} & {0} \\ {0} & {0} & {y}\end{array}\right|=x y$
Hence, $D$ is divisible by both $x$ and $y$