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: ages of two persons differ by 20 years. if 6 year ago, the elder one be 3 times as old the younger one, find their present age
Options: a. 12,28, b. 14,30, c. 16,36, d. 18,34, e. 19,34
[EX A]: c

[EX Q]: Problem: students at a school were on average 180 cm tall. the average female height was 170 cm, and the average male height was 182 cms. what was the ratio of men to women ?
Options: a. 5: 2, b. 5: 1, c. 4: 3, d. 4: 1, e. 3: 1
[EX A]: b

[EX Q]: Problem: two trains of equal lengths take 8 sec and 15 sec respectively to cross a telegraph post. if the length of each train be 120 m, in what time will they cross other travelling in opposite direction ?
Options: a. 22, b. 12, c. 77, d. 10, e. 21
[EX A]:
d