when the total products is at its maximum marginal products is

When the total product is at its maximum, the marginal product is zero. Marginal product refers to the additional output that is produced when an additional unit of input is added while keeping all other inputs constant. As more and more units of input are added, the marginal product eventually starts to decline. When the total product reaches its maximum point, the marginal product is zero, which means that no additional output is produced by adding an additional unit of input. Therefore, the correct answer is "zero".