Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[EX Q]: Problem: a bag of potatoes weighs 60 lbs divided by half of its weight. how much does the bag of potatoes weight ?
Options: a. 20 lb, b. 11 lb, c. 10 lb, d. 15 lb, e. 5 lb
[EX A]: b

[EX Q]: Problem: a and b go around a circular track of length 200 m on a cycle at speeds of 36 kmph and 72 kmph. after how much time will they meet for the first time at the starting point ?
Options: a. 120 sec, b. 198 sec, c. 178 sec, d. 20 sec, e. 276 sec
[EX A]: d

[EX Q]: Problem: a pharmaceutical company received $ 4 million in royalties on the first $ 20 million in sales of the generic equivalent of one of its products and then $ 9 million in royalties on the next $ 108 million in sales. by approximately what percent did the ratio of royalties to sales decrease from the first $ 20 million in sales to the next $ 108 million in sales ?
Options: a. 8 %, b. 15 %, c. 45 %, d. 52 %, e. 58 %
[EX A]:
e