If a firm moves from one point on a production isoquant to another point on the same isoquant， which of the following will certainly NOT happen？

If a firm moves from one point on a production isoquant to another point on the same isoquant， which of the following will certainly NOT happen？
A.a change in the level of output
B.a change in the ratio in which the inputs are combined
C.a change in the marginal products of the inputs
D.a change in the rate of technical substitution
正确答案：a change in the level of output