The corner points of the feasible region determined by the system of linear constraints are $(0, 0), (0, 40), (20, 40) (60, 20)$ and $(60, 0)$. If the objective function of an LPP is $Z = 4x + 3y$, then the maximum value is : (A) 200 (B) 300 (C) 240 (D) 120