\textbf{153.} The surjective proposition $\forall x \in \mathbb{N}, \exists y \in \mathbb{N}; P(x,y)$, with which expression of $P(x,y)$ is correct?
\medskip
(1) $y - x = 6$ \hfill (2) $x - y = 6$ \hfill (3) $x + y = 6$ \hfill (4) $xy = 6$
\medskip