AMC8 2027 - Self-practice Set 7 Question 23

The quiz-show prizes are 200 K, 400 K, 600 K, 1 M, 2 M, 3 M, 6 M, 10 M, 14 M, 22 M, 30 M, 40 M, 60 M, 85 M, 150 M. Which listed transition has the smallest proportional increase?