Match the code on the left with the precondition P$($x$,$y$)$ and postcondition Q$($x$,$y$)$ on the right that verifies its correctness.

t :$=$ x

x :$=2$y

y :$=2$t

t :$=$ x x:$=2$y y:$=2$t drop zone empty.

t :$=$ x

x :$=$ y$2$

y :$=$ t

t :$=$ x x:$=$y$2$ y:$=$t drop zone empty.

t :$=$ x

x :$=$ y $+2$

y :$=$ t

t :$=$ x x:$=$y$+2$ y:$=$t drop zone empty.

t :$=$ x

x :$=$ y $+2$

y :$=2$t