For the LPP Maximise $z=x+y$ subject to $x-y ≤-1,-x+y ≤ 2, x, y ≥ 0$, z has:

Max. value = $\frac{2}{3}$ Max. value = 5 Max. value = 11 No Max. value

No Max. value

The correct answer is Option (4) - No Max. value