For the products A, B, C, and D, which of the following could be a linear programming objective function? Z = 1A + 2BC + 3D Z = 1A + 2AB + 3ABC + 4ABCD Z = 1A + 2B + 3C + 4D Z = 1A + 2B/C + 3D Z = 1A + 2B − 1CD