z=4x+6y
Let's substitute the coordinates of each corner point into the objective function:
For point (0,2):z=4(0)+6(2)=12
For point (3,0):z=4(3)+6(0)=12
For point (6,0):z=4(6)+6(0)=24
For point (6,8):z=4(6)+6(8)=72
For point (0,5):z=4(0)+6(5)=30
From the evaluations, we can see that the minimum value of z occurs at two points, namely (0, 2) and (3, 0), both having a value of 12.
Therefore, the correct option is (D) only two points.