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.

Example Input: 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
Example Output: d

Example Input: Problem: the average runs scored by a batsman in 30 matches is 50. in the next 15 matches the batsman scored an average of 26 runs. find his average in all the 45 matches ?
Options: a. 31, b. 42, c. 29, d. 97, e. 27
Example Output: b

Example Input: Problem: a jogger running at 9 kmph along side a railway track is 260 metres ahead of the engine of a 120 metre long train running at 45 kmph in the same direction. in how much time will the train pass the jogger ?
Options: a. 3.6 sec, b. 38 sec, c. 36 sec, d. 72 sec, e. none of these
Example Output:
b