Which of the following can be deduced from the law of variable proportions when total output is rising?

The law of variable proportions states that as more units of a variable input are added to a fixed input, after a certain point the marginal product of the variable input will decrease. When total output is rising, it means that the variable input is adding more to the total output than the fixed input. Therefore, the marginal product (MP) of the variable input must be greater than the average product (AP) of all inputs. Hence, the correct option is: "MP is greater than AP."