We need to solve the equations two at a time. Observe that

For the point (0, 4) if we insert this point into first inequality we see that

is not true. Also for the point (6, 0) if we insert this point into the third inequality we see that

is not true. Therefore the points (0, 4) and (6, 0) do not belong the constraint set. The corner points for the constraint set are (0, 3), (-4, 0), (0, 0) and (-2/3, 10/3). Hence the correct answer is B.