Output of first decoder will be $O_0 = x'y', O_1 = x'y, O_2 = xy', O_3 = xy$
Although it should be mentioned which one is given as input to AND gates and which ones are given as input to OR gate, But if I assume AND gate is given $O_0$ and $O_1$, then $I_0 = x'y'.x'y = 0$ [any other selection of inputs to AND will also give $0$ as output]
Now, $O_2$ and $O_3$ are given as input to OR gate.
$I_1 = xy + xy' = x(y + y') = x$
$F = I_0z' + I_1z = 0.z' + xz = xz$
PS:) Any other selection of inputs to AND and OR gates is also valid, but it doesn't produce any output from options given.
