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: aaron will jog from home at 2 miles per hour and then walk back home by the same route at 4 miles per hour. how many miles from home can aaron jog so that he spends a total of 3 hours jogging and walking ?
Options: a. 5, b. 7, c. 3, d. 9, e. 10
[EX A]: c

[EX Q]: Problem: three 6 faced dice are thrown together. the probability that exactly two dice show the same number on them is
Options: a. 5 / 15, b. 5 / 12, c. 5 / 19, d. 5 / 12, e. 5 / 11
[EX A]: b

[EX Q]: Problem: in what time will a train 120 m long cross an electric pole, it its speed be 121 km / hr ?
Options: a. 2.5, b. 2.7, c. 2.9, d. 3.6, e. 2.1
[EX A]:
d