it is known that the cost function of an enterprise is C = q3-9q2 + 30g + 25, where C is the cost (unit: thousand dollars), q is the output (unit: T), and the minimum value of average variable cost C (unit: thousand dollars) is obtained.

Consider the functions below. function 1 function 2 function 3 select the statement which is true about the functions over the interval [1, 2] a b function 3 has the highest average rate of change function 2 and function 3 have the same average rate of change. function and function 3 have the same average rate of change function 2 has the lowest average rate of change d.