In Linear Programming Problems (LPPs), optimal solutions are found at the vertices of the feasible region. The provided constraints are: 1. \(x + y \leq 4\), defining a line through \((4, 0)\) and \((0, 4)\). 2. \(3x + 3y \geq 18\), defining a line through \((6, 0)\) and \((0, 6)\). 3. \(x, y \geq 0\), confining the solution to the first quadrant. The feasible region is the intersection of these constraints. The solution lies within the combined area of $\triangle AOB$ and the unbounded shaded region. Consequently, option (4) is the correct choice.